xref: /OK3568_Linux_fs/kernel/drivers/bus/mips_cdmm.c (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593Smuzhiyun /*
2*4882a593Smuzhiyun  * Bus driver for MIPS Common Device Memory Map (CDMM).
3*4882a593Smuzhiyun  *
4*4882a593Smuzhiyun  * Copyright (C) 2014-2015 Imagination Technologies Ltd.
5*4882a593Smuzhiyun  *
6*4882a593Smuzhiyun  * This file is subject to the terms and conditions of the GNU General Public
7*4882a593Smuzhiyun  * License.  See the file "COPYING" in the main directory of this archive
8*4882a593Smuzhiyun  * for more details.
9*4882a593Smuzhiyun  */
10*4882a593Smuzhiyun 
11*4882a593Smuzhiyun #include <linux/atomic.h>
12*4882a593Smuzhiyun #include <linux/err.h>
13*4882a593Smuzhiyun #include <linux/cpu.h>
14*4882a593Smuzhiyun #include <linux/cpumask.h>
15*4882a593Smuzhiyun #include <linux/io.h>
16*4882a593Smuzhiyun #include <linux/of_address.h>
17*4882a593Smuzhiyun #include <linux/of.h>
18*4882a593Smuzhiyun #include <linux/platform_device.h>
19*4882a593Smuzhiyun #include <linux/slab.h>
20*4882a593Smuzhiyun #include <linux/smp.h>
21*4882a593Smuzhiyun #include <asm/cdmm.h>
22*4882a593Smuzhiyun #include <asm/hazards.h>
23*4882a593Smuzhiyun #include <asm/mipsregs.h>
24*4882a593Smuzhiyun 
25*4882a593Smuzhiyun /* Access control and status register fields */
26*4882a593Smuzhiyun #define CDMM_ACSR_DEVTYPE_SHIFT	24
27*4882a593Smuzhiyun #define CDMM_ACSR_DEVTYPE	(255ul << CDMM_ACSR_DEVTYPE_SHIFT)
28*4882a593Smuzhiyun #define CDMM_ACSR_DEVSIZE_SHIFT	16
29*4882a593Smuzhiyun #define CDMM_ACSR_DEVSIZE	(31ul << CDMM_ACSR_DEVSIZE_SHIFT)
30*4882a593Smuzhiyun #define CDMM_ACSR_DEVREV_SHIFT	12
31*4882a593Smuzhiyun #define CDMM_ACSR_DEVREV	(15ul << CDMM_ACSR_DEVREV_SHIFT)
32*4882a593Smuzhiyun #define CDMM_ACSR_UW		(1ul << 3)
33*4882a593Smuzhiyun #define CDMM_ACSR_UR		(1ul << 2)
34*4882a593Smuzhiyun #define CDMM_ACSR_SW		(1ul << 1)
35*4882a593Smuzhiyun #define CDMM_ACSR_SR		(1ul << 0)
36*4882a593Smuzhiyun 
37*4882a593Smuzhiyun /* Each block of device registers is 64 bytes */
38*4882a593Smuzhiyun #define CDMM_DRB_SIZE		64
39*4882a593Smuzhiyun 
40*4882a593Smuzhiyun #define to_mips_cdmm_driver(d)	container_of(d, struct mips_cdmm_driver, drv)
41*4882a593Smuzhiyun 
42*4882a593Smuzhiyun /* Default physical base address */
43*4882a593Smuzhiyun static phys_addr_t mips_cdmm_default_base;
44*4882a593Smuzhiyun 
45*4882a593Smuzhiyun /* Bus operations */
46*4882a593Smuzhiyun 
47*4882a593Smuzhiyun static const struct mips_cdmm_device_id *
mips_cdmm_lookup(const struct mips_cdmm_device_id * table,struct mips_cdmm_device * dev)48*4882a593Smuzhiyun mips_cdmm_lookup(const struct mips_cdmm_device_id *table,
49*4882a593Smuzhiyun 		 struct mips_cdmm_device *dev)
50*4882a593Smuzhiyun {
51*4882a593Smuzhiyun 	int ret = 0;
52*4882a593Smuzhiyun 
53*4882a593Smuzhiyun 	for (; table->type; ++table) {
54*4882a593Smuzhiyun 		ret = (dev->type == table->type);
55*4882a593Smuzhiyun 		if (ret)
56*4882a593Smuzhiyun 			break;
57*4882a593Smuzhiyun 	}
58*4882a593Smuzhiyun 
59*4882a593Smuzhiyun 	return ret ? table : NULL;
60*4882a593Smuzhiyun }
61*4882a593Smuzhiyun 
mips_cdmm_match(struct device * dev,struct device_driver * drv)62*4882a593Smuzhiyun static int mips_cdmm_match(struct device *dev, struct device_driver *drv)
63*4882a593Smuzhiyun {
64*4882a593Smuzhiyun 	struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);
65*4882a593Smuzhiyun 	struct mips_cdmm_driver *cdrv = to_mips_cdmm_driver(drv);
66*4882a593Smuzhiyun 
67*4882a593Smuzhiyun 	return mips_cdmm_lookup(cdrv->id_table, cdev) != NULL;
68*4882a593Smuzhiyun }
69*4882a593Smuzhiyun 
mips_cdmm_uevent(struct device * dev,struct kobj_uevent_env * env)70*4882a593Smuzhiyun static int mips_cdmm_uevent(struct device *dev, struct kobj_uevent_env *env)
71*4882a593Smuzhiyun {
72*4882a593Smuzhiyun 	struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);
73*4882a593Smuzhiyun 	int retval = 0;
74*4882a593Smuzhiyun 
75*4882a593Smuzhiyun 	retval = add_uevent_var(env, "CDMM_CPU=%u", cdev->cpu);
76*4882a593Smuzhiyun 	if (retval)
77*4882a593Smuzhiyun 		return retval;
78*4882a593Smuzhiyun 
79*4882a593Smuzhiyun 	retval = add_uevent_var(env, "CDMM_TYPE=0x%02x", cdev->type);
80*4882a593Smuzhiyun 	if (retval)
81*4882a593Smuzhiyun 		return retval;
82*4882a593Smuzhiyun 
83*4882a593Smuzhiyun 	retval = add_uevent_var(env, "CDMM_REV=%u", cdev->rev);
84*4882a593Smuzhiyun 	if (retval)
85*4882a593Smuzhiyun 		return retval;
86*4882a593Smuzhiyun 
87*4882a593Smuzhiyun 	retval = add_uevent_var(env, "MODALIAS=mipscdmm:t%02X", cdev->type);
88*4882a593Smuzhiyun 	return retval;
89*4882a593Smuzhiyun }
90*4882a593Smuzhiyun 
91*4882a593Smuzhiyun /* Device attributes */
92*4882a593Smuzhiyun 
93*4882a593Smuzhiyun #define CDMM_ATTR(name, fmt, arg...)					\
94*4882a593Smuzhiyun static ssize_t name##_show(struct device *_dev,				\
95*4882a593Smuzhiyun 			   struct device_attribute *attr, char *buf)	\
96*4882a593Smuzhiyun {									\
97*4882a593Smuzhiyun 	struct mips_cdmm_device *dev = to_mips_cdmm_device(_dev);	\
98*4882a593Smuzhiyun 	return sprintf(buf, fmt, arg);					\
99*4882a593Smuzhiyun }									\
100*4882a593Smuzhiyun static DEVICE_ATTR_RO(name);
101*4882a593Smuzhiyun 
102*4882a593Smuzhiyun CDMM_ATTR(cpu, "%u\n", dev->cpu);
103*4882a593Smuzhiyun CDMM_ATTR(type, "0x%02x\n", dev->type);
104*4882a593Smuzhiyun CDMM_ATTR(revision, "%u\n", dev->rev);
105*4882a593Smuzhiyun CDMM_ATTR(modalias, "mipscdmm:t%02X\n", dev->type);
106*4882a593Smuzhiyun CDMM_ATTR(resource, "\t%016llx\t%016llx\t%016lx\n",
107*4882a593Smuzhiyun 	  (unsigned long long)dev->res.start,
108*4882a593Smuzhiyun 	  (unsigned long long)dev->res.end,
109*4882a593Smuzhiyun 	  dev->res.flags);
110*4882a593Smuzhiyun 
111*4882a593Smuzhiyun static struct attribute *mips_cdmm_dev_attrs[] = {
112*4882a593Smuzhiyun 	&dev_attr_cpu.attr,
113*4882a593Smuzhiyun 	&dev_attr_type.attr,
114*4882a593Smuzhiyun 	&dev_attr_revision.attr,
115*4882a593Smuzhiyun 	&dev_attr_modalias.attr,
116*4882a593Smuzhiyun 	&dev_attr_resource.attr,
117*4882a593Smuzhiyun 	NULL,
118*4882a593Smuzhiyun };
119*4882a593Smuzhiyun ATTRIBUTE_GROUPS(mips_cdmm_dev);
120*4882a593Smuzhiyun 
121*4882a593Smuzhiyun struct bus_type mips_cdmm_bustype = {
122*4882a593Smuzhiyun 	.name		= "cdmm",
123*4882a593Smuzhiyun 	.dev_groups	= mips_cdmm_dev_groups,
124*4882a593Smuzhiyun 	.match		= mips_cdmm_match,
125*4882a593Smuzhiyun 	.uevent		= mips_cdmm_uevent,
126*4882a593Smuzhiyun };
127*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(mips_cdmm_bustype);
128*4882a593Smuzhiyun 
129*4882a593Smuzhiyun /*
130*4882a593Smuzhiyun  * Standard driver callback helpers.
131*4882a593Smuzhiyun  *
132*4882a593Smuzhiyun  * All the CDMM driver callbacks need to be executed on the appropriate CPU from
133*4882a593Smuzhiyun  * workqueues. For the standard driver callbacks we need a work function
134*4882a593Smuzhiyun  * (mips_cdmm_{void,int}_work()) to do the actual call from the right CPU, and a
135*4882a593Smuzhiyun  * wrapper function (generated with BUILD_PERCPU_HELPER) to arrange for the work
136*4882a593Smuzhiyun  * function to be called on that CPU.
137*4882a593Smuzhiyun  */
138*4882a593Smuzhiyun 
139*4882a593Smuzhiyun /**
140*4882a593Smuzhiyun  * struct mips_cdmm_work_dev - Data for per-device call work.
141*4882a593Smuzhiyun  * @fn:		CDMM driver callback function to call for the device.
142*4882a593Smuzhiyun  * @dev:	CDMM device to pass to @fn.
143*4882a593Smuzhiyun  */
144*4882a593Smuzhiyun struct mips_cdmm_work_dev {
145*4882a593Smuzhiyun 	void			*fn;
146*4882a593Smuzhiyun 	struct mips_cdmm_device *dev;
147*4882a593Smuzhiyun };
148*4882a593Smuzhiyun 
149*4882a593Smuzhiyun /**
150*4882a593Smuzhiyun  * mips_cdmm_void_work() - Call a void returning CDMM driver callback.
151*4882a593Smuzhiyun  * @data:	struct mips_cdmm_work_dev pointer.
152*4882a593Smuzhiyun  *
153*4882a593Smuzhiyun  * A work_on_cpu() callback function to call an arbitrary CDMM driver callback
154*4882a593Smuzhiyun  * function which doesn't return a value.
155*4882a593Smuzhiyun  */
mips_cdmm_void_work(void * data)156*4882a593Smuzhiyun static long mips_cdmm_void_work(void *data)
157*4882a593Smuzhiyun {
158*4882a593Smuzhiyun 	struct mips_cdmm_work_dev *work = data;
159*4882a593Smuzhiyun 	void (*fn)(struct mips_cdmm_device *) = work->fn;
160*4882a593Smuzhiyun 
161*4882a593Smuzhiyun 	fn(work->dev);
162*4882a593Smuzhiyun 	return 0;
163*4882a593Smuzhiyun }
164*4882a593Smuzhiyun 
165*4882a593Smuzhiyun /**
166*4882a593Smuzhiyun  * mips_cdmm_int_work() - Call an int returning CDMM driver callback.
167*4882a593Smuzhiyun  * @data:	struct mips_cdmm_work_dev pointer.
168*4882a593Smuzhiyun  *
169*4882a593Smuzhiyun  * A work_on_cpu() callback function to call an arbitrary CDMM driver callback
170*4882a593Smuzhiyun  * function which returns an int.
171*4882a593Smuzhiyun  */
mips_cdmm_int_work(void * data)172*4882a593Smuzhiyun static long mips_cdmm_int_work(void *data)
173*4882a593Smuzhiyun {
174*4882a593Smuzhiyun 	struct mips_cdmm_work_dev *work = data;
175*4882a593Smuzhiyun 	int (*fn)(struct mips_cdmm_device *) = work->fn;
176*4882a593Smuzhiyun 
177*4882a593Smuzhiyun 	return fn(work->dev);
178*4882a593Smuzhiyun }
179*4882a593Smuzhiyun 
180*4882a593Smuzhiyun #define _BUILD_RET_void
181*4882a593Smuzhiyun #define _BUILD_RET_int	return
182*4882a593Smuzhiyun 
183*4882a593Smuzhiyun /**
184*4882a593Smuzhiyun  * BUILD_PERCPU_HELPER() - Helper to call a CDMM driver callback on right CPU.
185*4882a593Smuzhiyun  * @_ret:	Return type (void or int).
186*4882a593Smuzhiyun  * @_name:	Name of CDMM driver callback function.
187*4882a593Smuzhiyun  *
188*4882a593Smuzhiyun  * Generates a specific device callback function to call a CDMM driver callback
189*4882a593Smuzhiyun  * function on the appropriate CPU for the device, and if applicable return the
190*4882a593Smuzhiyun  * result.
191*4882a593Smuzhiyun  */
192*4882a593Smuzhiyun #define BUILD_PERCPU_HELPER(_ret, _name)				\
193*4882a593Smuzhiyun static _ret mips_cdmm_##_name(struct device *dev)			\
194*4882a593Smuzhiyun {									\
195*4882a593Smuzhiyun 	struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);	\
196*4882a593Smuzhiyun 	struct mips_cdmm_driver *cdrv = to_mips_cdmm_driver(dev->driver); \
197*4882a593Smuzhiyun 	struct mips_cdmm_work_dev work = {				\
198*4882a593Smuzhiyun 		.fn	= cdrv->_name,					\
199*4882a593Smuzhiyun 		.dev	= cdev,						\
200*4882a593Smuzhiyun 	};								\
201*4882a593Smuzhiyun 									\
202*4882a593Smuzhiyun 	_BUILD_RET_##_ret work_on_cpu(cdev->cpu,			\
203*4882a593Smuzhiyun 				      mips_cdmm_##_ret##_work, &work);	\
204*4882a593Smuzhiyun }
205*4882a593Smuzhiyun 
206*4882a593Smuzhiyun /* Driver callback functions */
BUILD_PERCPU_HELPER(int,probe)207*4882a593Smuzhiyun BUILD_PERCPU_HELPER(int, probe)     /* int mips_cdmm_probe(struct device) */
208*4882a593Smuzhiyun BUILD_PERCPU_HELPER(int, remove)    /* int mips_cdmm_remove(struct device) */
209*4882a593Smuzhiyun BUILD_PERCPU_HELPER(void, shutdown) /* void mips_cdmm_shutdown(struct device) */
210*4882a593Smuzhiyun 
211*4882a593Smuzhiyun 
212*4882a593Smuzhiyun /* Driver registration */
213*4882a593Smuzhiyun 
214*4882a593Smuzhiyun /**
215*4882a593Smuzhiyun  * mips_cdmm_driver_register() - Register a CDMM driver.
216*4882a593Smuzhiyun  * @drv:	CDMM driver information.
217*4882a593Smuzhiyun  *
218*4882a593Smuzhiyun  * Register a CDMM driver with the CDMM subsystem. The driver will be informed
219*4882a593Smuzhiyun  * of matching devices which are discovered.
220*4882a593Smuzhiyun  *
221*4882a593Smuzhiyun  * Returns:	0 on success.
222*4882a593Smuzhiyun  */
223*4882a593Smuzhiyun int mips_cdmm_driver_register(struct mips_cdmm_driver *drv)
224*4882a593Smuzhiyun {
225*4882a593Smuzhiyun 	drv->drv.bus = &mips_cdmm_bustype;
226*4882a593Smuzhiyun 
227*4882a593Smuzhiyun 	if (drv->probe)
228*4882a593Smuzhiyun 		drv->drv.probe = mips_cdmm_probe;
229*4882a593Smuzhiyun 	if (drv->remove)
230*4882a593Smuzhiyun 		drv->drv.remove = mips_cdmm_remove;
231*4882a593Smuzhiyun 	if (drv->shutdown)
232*4882a593Smuzhiyun 		drv->drv.shutdown = mips_cdmm_shutdown;
233*4882a593Smuzhiyun 
234*4882a593Smuzhiyun 	return driver_register(&drv->drv);
235*4882a593Smuzhiyun }
236*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(mips_cdmm_driver_register);
237*4882a593Smuzhiyun 
238*4882a593Smuzhiyun /**
239*4882a593Smuzhiyun  * mips_cdmm_driver_unregister() - Unregister a CDMM driver.
240*4882a593Smuzhiyun  * @drv:	CDMM driver information.
241*4882a593Smuzhiyun  *
242*4882a593Smuzhiyun  * Unregister a CDMM driver from the CDMM subsystem.
243*4882a593Smuzhiyun  */
mips_cdmm_driver_unregister(struct mips_cdmm_driver * drv)244*4882a593Smuzhiyun void mips_cdmm_driver_unregister(struct mips_cdmm_driver *drv)
245*4882a593Smuzhiyun {
246*4882a593Smuzhiyun 	driver_unregister(&drv->drv);
247*4882a593Smuzhiyun }
248*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(mips_cdmm_driver_unregister);
249*4882a593Smuzhiyun 
250*4882a593Smuzhiyun 
251*4882a593Smuzhiyun /* CDMM initialisation and bus discovery */
252*4882a593Smuzhiyun 
253*4882a593Smuzhiyun /**
254*4882a593Smuzhiyun  * struct mips_cdmm_bus - Info about CDMM bus.
255*4882a593Smuzhiyun  * @phys:		Physical address at which it is mapped.
256*4882a593Smuzhiyun  * @regs:		Virtual address where registers can be accessed.
257*4882a593Smuzhiyun  * @drbs:		Total number of DRBs.
258*4882a593Smuzhiyun  * @drbs_reserved:	Number of DRBs reserved.
259*4882a593Smuzhiyun  * @discovered:		Whether the devices on the bus have been discovered yet.
260*4882a593Smuzhiyun  * @offline:		Whether the CDMM bus is going offline (or very early
261*4882a593Smuzhiyun  *			coming back online), in which case it should be
262*4882a593Smuzhiyun  *			reconfigured each time.
263*4882a593Smuzhiyun  */
264*4882a593Smuzhiyun struct mips_cdmm_bus {
265*4882a593Smuzhiyun 	phys_addr_t	 phys;
266*4882a593Smuzhiyun 	void __iomem	*regs;
267*4882a593Smuzhiyun 	unsigned int	 drbs;
268*4882a593Smuzhiyun 	unsigned int	 drbs_reserved;
269*4882a593Smuzhiyun 	bool		 discovered;
270*4882a593Smuzhiyun 	bool		 offline;
271*4882a593Smuzhiyun };
272*4882a593Smuzhiyun 
273*4882a593Smuzhiyun static struct mips_cdmm_bus mips_cdmm_boot_bus;
274*4882a593Smuzhiyun static DEFINE_PER_CPU(struct mips_cdmm_bus *, mips_cdmm_buses);
275*4882a593Smuzhiyun static atomic_t mips_cdmm_next_id = ATOMIC_INIT(-1);
276*4882a593Smuzhiyun 
277*4882a593Smuzhiyun /**
278*4882a593Smuzhiyun  * mips_cdmm_get_bus() - Get the per-CPU CDMM bus information.
279*4882a593Smuzhiyun  *
280*4882a593Smuzhiyun  * Get information about the per-CPU CDMM bus, if the bus is present.
281*4882a593Smuzhiyun  *
282*4882a593Smuzhiyun  * The caller must prevent migration to another CPU, either by disabling
283*4882a593Smuzhiyun  * pre-emption or by running from a pinned kernel thread.
284*4882a593Smuzhiyun  *
285*4882a593Smuzhiyun  * Returns:	Pointer to CDMM bus information for the current CPU.
286*4882a593Smuzhiyun  *		May return ERR_PTR(-errno) in case of error, so check with
287*4882a593Smuzhiyun  *		IS_ERR().
288*4882a593Smuzhiyun  */
mips_cdmm_get_bus(void)289*4882a593Smuzhiyun static struct mips_cdmm_bus *mips_cdmm_get_bus(void)
290*4882a593Smuzhiyun {
291*4882a593Smuzhiyun 	struct mips_cdmm_bus *bus, **bus_p;
292*4882a593Smuzhiyun 	unsigned long flags;
293*4882a593Smuzhiyun 	unsigned int cpu;
294*4882a593Smuzhiyun 
295*4882a593Smuzhiyun 	if (!cpu_has_cdmm)
296*4882a593Smuzhiyun 		return ERR_PTR(-ENODEV);
297*4882a593Smuzhiyun 
298*4882a593Smuzhiyun 	cpu = smp_processor_id();
299*4882a593Smuzhiyun 	/* Avoid early use of per-cpu primitives before initialised */
300*4882a593Smuzhiyun 	if (cpu == 0)
301*4882a593Smuzhiyun 		return &mips_cdmm_boot_bus;
302*4882a593Smuzhiyun 
303*4882a593Smuzhiyun 	/* Get bus pointer */
304*4882a593Smuzhiyun 	bus_p = per_cpu_ptr(&mips_cdmm_buses, cpu);
305*4882a593Smuzhiyun 	local_irq_save(flags);
306*4882a593Smuzhiyun 	bus = *bus_p;
307*4882a593Smuzhiyun 	/* Attempt allocation if NULL */
308*4882a593Smuzhiyun 	if (unlikely(!bus)) {
309*4882a593Smuzhiyun 		bus = kzalloc(sizeof(*bus), GFP_ATOMIC);
310*4882a593Smuzhiyun 		if (unlikely(!bus))
311*4882a593Smuzhiyun 			bus = ERR_PTR(-ENOMEM);
312*4882a593Smuzhiyun 		else
313*4882a593Smuzhiyun 			*bus_p = bus;
314*4882a593Smuzhiyun 	}
315*4882a593Smuzhiyun 	local_irq_restore(flags);
316*4882a593Smuzhiyun 	return bus;
317*4882a593Smuzhiyun }
318*4882a593Smuzhiyun 
319*4882a593Smuzhiyun /**
320*4882a593Smuzhiyun  * mips_cdmm_cur_base() - Find current physical base address of CDMM region.
321*4882a593Smuzhiyun  *
322*4882a593Smuzhiyun  * Returns:	Physical base address of CDMM region according to cdmmbase CP0
323*4882a593Smuzhiyun  *		register, or 0 if the CDMM region is disabled.
324*4882a593Smuzhiyun  */
mips_cdmm_cur_base(void)325*4882a593Smuzhiyun static phys_addr_t mips_cdmm_cur_base(void)
326*4882a593Smuzhiyun {
327*4882a593Smuzhiyun 	unsigned long cdmmbase = read_c0_cdmmbase();
328*4882a593Smuzhiyun 
329*4882a593Smuzhiyun 	if (!(cdmmbase & MIPS_CDMMBASE_EN))
330*4882a593Smuzhiyun 		return 0;
331*4882a593Smuzhiyun 
332*4882a593Smuzhiyun 	return (cdmmbase >> MIPS_CDMMBASE_ADDR_SHIFT)
333*4882a593Smuzhiyun 		<< MIPS_CDMMBASE_ADDR_START;
334*4882a593Smuzhiyun }
335*4882a593Smuzhiyun 
336*4882a593Smuzhiyun /**
337*4882a593Smuzhiyun  * mips_cdmm_phys_base() - Choose a physical base address for CDMM region.
338*4882a593Smuzhiyun  *
339*4882a593Smuzhiyun  * Picking a suitable physical address at which to map the CDMM region is
340*4882a593Smuzhiyun  * platform specific, so this weak function can be overridden by platform
341*4882a593Smuzhiyun  * code to pick a suitable value if none is configured by the bootloader.
342*4882a593Smuzhiyun  * By default this method tries to find a CDMM-specific node in the system
343*4882a593Smuzhiyun  * dtb. Note that this won't work for early serial console.
344*4882a593Smuzhiyun  */
mips_cdmm_phys_base(void)345*4882a593Smuzhiyun phys_addr_t __weak mips_cdmm_phys_base(void)
346*4882a593Smuzhiyun {
347*4882a593Smuzhiyun 	struct device_node *np;
348*4882a593Smuzhiyun 	struct resource res;
349*4882a593Smuzhiyun 	int err;
350*4882a593Smuzhiyun 
351*4882a593Smuzhiyun 	np = of_find_compatible_node(NULL, NULL, "mti,mips-cdmm");
352*4882a593Smuzhiyun 	if (np) {
353*4882a593Smuzhiyun 		err = of_address_to_resource(np, 0, &res);
354*4882a593Smuzhiyun 		of_node_put(np);
355*4882a593Smuzhiyun 		if (!err)
356*4882a593Smuzhiyun 			return res.start;
357*4882a593Smuzhiyun 	}
358*4882a593Smuzhiyun 
359*4882a593Smuzhiyun 	return 0;
360*4882a593Smuzhiyun }
361*4882a593Smuzhiyun 
362*4882a593Smuzhiyun /**
363*4882a593Smuzhiyun  * mips_cdmm_setup() - Ensure the CDMM bus is initialised and usable.
364*4882a593Smuzhiyun  * @bus:	Pointer to bus information for current CPU.
365*4882a593Smuzhiyun  *		IS_ERR(bus) is checked, so no need for caller to check.
366*4882a593Smuzhiyun  *
367*4882a593Smuzhiyun  * The caller must prevent migration to another CPU, either by disabling
368*4882a593Smuzhiyun  * pre-emption or by running from a pinned kernel thread.
369*4882a593Smuzhiyun  *
370*4882a593Smuzhiyun  * Returns	0 on success, -errno on failure.
371*4882a593Smuzhiyun  */
mips_cdmm_setup(struct mips_cdmm_bus * bus)372*4882a593Smuzhiyun static int mips_cdmm_setup(struct mips_cdmm_bus *bus)
373*4882a593Smuzhiyun {
374*4882a593Smuzhiyun 	unsigned long cdmmbase, flags;
375*4882a593Smuzhiyun 	int ret = 0;
376*4882a593Smuzhiyun 
377*4882a593Smuzhiyun 	if (IS_ERR(bus))
378*4882a593Smuzhiyun 		return PTR_ERR(bus);
379*4882a593Smuzhiyun 
380*4882a593Smuzhiyun 	local_irq_save(flags);
381*4882a593Smuzhiyun 	/* Don't set up bus a second time unless marked offline */
382*4882a593Smuzhiyun 	if (bus->offline) {
383*4882a593Smuzhiyun 		/* If CDMM region is still set up, nothing to do */
384*4882a593Smuzhiyun 		if (bus->phys == mips_cdmm_cur_base())
385*4882a593Smuzhiyun 			goto out;
386*4882a593Smuzhiyun 		/*
387*4882a593Smuzhiyun 		 * The CDMM region isn't set up as expected, so it needs
388*4882a593Smuzhiyun 		 * reconfiguring, but then we can stop checking it.
389*4882a593Smuzhiyun 		 */
390*4882a593Smuzhiyun 		bus->offline = false;
391*4882a593Smuzhiyun 	} else if (bus->phys > 1) {
392*4882a593Smuzhiyun 		goto out;
393*4882a593Smuzhiyun 	}
394*4882a593Smuzhiyun 
395*4882a593Smuzhiyun 	/* If the CDMM region is already configured, inherit that setup */
396*4882a593Smuzhiyun 	if (!bus->phys)
397*4882a593Smuzhiyun 		bus->phys = mips_cdmm_cur_base();
398*4882a593Smuzhiyun 	/* Otherwise, ask platform code for suggestions */
399*4882a593Smuzhiyun 	if (!bus->phys)
400*4882a593Smuzhiyun 		bus->phys = mips_cdmm_phys_base();
401*4882a593Smuzhiyun 	/* Otherwise, copy what other CPUs have done */
402*4882a593Smuzhiyun 	if (!bus->phys)
403*4882a593Smuzhiyun 		bus->phys = mips_cdmm_default_base;
404*4882a593Smuzhiyun 	/* Otherwise, complain once */
405*4882a593Smuzhiyun 	if (!bus->phys) {
406*4882a593Smuzhiyun 		bus->phys = 1;
407*4882a593Smuzhiyun 		/*
408*4882a593Smuzhiyun 		 * If you hit this, either your bootloader needs to set up the
409*4882a593Smuzhiyun 		 * CDMM on the boot CPU, or else you need to implement
410*4882a593Smuzhiyun 		 * mips_cdmm_phys_base() for your platform (see asm/cdmm.h).
411*4882a593Smuzhiyun 		 */
412*4882a593Smuzhiyun 		pr_err("cdmm%u: Failed to choose a physical base\n",
413*4882a593Smuzhiyun 		       smp_processor_id());
414*4882a593Smuzhiyun 	}
415*4882a593Smuzhiyun 	/* Already complained? */
416*4882a593Smuzhiyun 	if (bus->phys == 1) {
417*4882a593Smuzhiyun 		ret = -ENOMEM;
418*4882a593Smuzhiyun 		goto out;
419*4882a593Smuzhiyun 	}
420*4882a593Smuzhiyun 	/* Record our success for other CPUs to copy */
421*4882a593Smuzhiyun 	mips_cdmm_default_base = bus->phys;
422*4882a593Smuzhiyun 
423*4882a593Smuzhiyun 	pr_debug("cdmm%u: Enabling CDMM region at %pa\n",
424*4882a593Smuzhiyun 		 smp_processor_id(), &bus->phys);
425*4882a593Smuzhiyun 
426*4882a593Smuzhiyun 	/* Enable CDMM */
427*4882a593Smuzhiyun 	cdmmbase = read_c0_cdmmbase();
428*4882a593Smuzhiyun 	cdmmbase &= (1ul << MIPS_CDMMBASE_ADDR_SHIFT) - 1;
429*4882a593Smuzhiyun 	cdmmbase |= (bus->phys >> MIPS_CDMMBASE_ADDR_START)
430*4882a593Smuzhiyun 			<< MIPS_CDMMBASE_ADDR_SHIFT;
431*4882a593Smuzhiyun 	cdmmbase |= MIPS_CDMMBASE_EN;
432*4882a593Smuzhiyun 	write_c0_cdmmbase(cdmmbase);
433*4882a593Smuzhiyun 	tlbw_use_hazard();
434*4882a593Smuzhiyun 
435*4882a593Smuzhiyun 	bus->regs = (void __iomem *)CKSEG1ADDR(bus->phys);
436*4882a593Smuzhiyun 	bus->drbs = 1 + ((cdmmbase & MIPS_CDMMBASE_SIZE) >>
437*4882a593Smuzhiyun 			 MIPS_CDMMBASE_SIZE_SHIFT);
438*4882a593Smuzhiyun 	bus->drbs_reserved = !!(cdmmbase & MIPS_CDMMBASE_CI);
439*4882a593Smuzhiyun 
440*4882a593Smuzhiyun out:
441*4882a593Smuzhiyun 	local_irq_restore(flags);
442*4882a593Smuzhiyun 	return ret;
443*4882a593Smuzhiyun }
444*4882a593Smuzhiyun 
445*4882a593Smuzhiyun /**
446*4882a593Smuzhiyun  * mips_cdmm_early_probe() - Minimally probe for a specific device on CDMM.
447*4882a593Smuzhiyun  * @dev_type:	CDMM type code to look for.
448*4882a593Smuzhiyun  *
449*4882a593Smuzhiyun  * Minimally configure the in-CPU Common Device Memory Map (CDMM) and look for a
450*4882a593Smuzhiyun  * specific device. This can be used to find a device very early in boot for
451*4882a593Smuzhiyun  * example to configure an early FDC console device.
452*4882a593Smuzhiyun  *
453*4882a593Smuzhiyun  * The caller must prevent migration to another CPU, either by disabling
454*4882a593Smuzhiyun  * pre-emption or by running from a pinned kernel thread.
455*4882a593Smuzhiyun  *
456*4882a593Smuzhiyun  * Returns:	MMIO pointer to device memory. The caller can read the ACSR
457*4882a593Smuzhiyun  *		register to find more information about the device (such as the
458*4882a593Smuzhiyun  *		version number or the number of blocks).
459*4882a593Smuzhiyun  *		May return IOMEM_ERR_PTR(-errno) in case of error, so check with
460*4882a593Smuzhiyun  *		IS_ERR().
461*4882a593Smuzhiyun  */
mips_cdmm_early_probe(unsigned int dev_type)462*4882a593Smuzhiyun void __iomem *mips_cdmm_early_probe(unsigned int dev_type)
463*4882a593Smuzhiyun {
464*4882a593Smuzhiyun 	struct mips_cdmm_bus *bus;
465*4882a593Smuzhiyun 	void __iomem *cdmm;
466*4882a593Smuzhiyun 	u32 acsr;
467*4882a593Smuzhiyun 	unsigned int drb, type, size;
468*4882a593Smuzhiyun 	int err;
469*4882a593Smuzhiyun 
470*4882a593Smuzhiyun 	if (WARN_ON(!dev_type))
471*4882a593Smuzhiyun 		return IOMEM_ERR_PTR(-ENODEV);
472*4882a593Smuzhiyun 
473*4882a593Smuzhiyun 	bus = mips_cdmm_get_bus();
474*4882a593Smuzhiyun 	err = mips_cdmm_setup(bus);
475*4882a593Smuzhiyun 	if (err)
476*4882a593Smuzhiyun 		return IOMEM_ERR_PTR(err);
477*4882a593Smuzhiyun 
478*4882a593Smuzhiyun 	/* Skip the first block if it's reserved for more registers */
479*4882a593Smuzhiyun 	drb = bus->drbs_reserved;
480*4882a593Smuzhiyun 	cdmm = bus->regs;
481*4882a593Smuzhiyun 
482*4882a593Smuzhiyun 	/* Look for a specific device type */
483*4882a593Smuzhiyun 	for (; drb < bus->drbs; drb += size + 1) {
484*4882a593Smuzhiyun 		acsr = __raw_readl(cdmm + drb * CDMM_DRB_SIZE);
485*4882a593Smuzhiyun 		type = (acsr & CDMM_ACSR_DEVTYPE) >> CDMM_ACSR_DEVTYPE_SHIFT;
486*4882a593Smuzhiyun 		if (type == dev_type)
487*4882a593Smuzhiyun 			return cdmm + drb * CDMM_DRB_SIZE;
488*4882a593Smuzhiyun 		size = (acsr & CDMM_ACSR_DEVSIZE) >> CDMM_ACSR_DEVSIZE_SHIFT;
489*4882a593Smuzhiyun 	}
490*4882a593Smuzhiyun 
491*4882a593Smuzhiyun 	return IOMEM_ERR_PTR(-ENODEV);
492*4882a593Smuzhiyun }
493*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(mips_cdmm_early_probe);
494*4882a593Smuzhiyun 
495*4882a593Smuzhiyun /**
496*4882a593Smuzhiyun  * mips_cdmm_release() - Release a removed CDMM device.
497*4882a593Smuzhiyun  * @dev:	Device object
498*4882a593Smuzhiyun  *
499*4882a593Smuzhiyun  * Clean up the struct mips_cdmm_device for an unused CDMM device. This is
500*4882a593Smuzhiyun  * called automatically by the driver core when a device is removed.
501*4882a593Smuzhiyun  */
mips_cdmm_release(struct device * dev)502*4882a593Smuzhiyun static void mips_cdmm_release(struct device *dev)
503*4882a593Smuzhiyun {
504*4882a593Smuzhiyun 	struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);
505*4882a593Smuzhiyun 
506*4882a593Smuzhiyun 	kfree(cdev);
507*4882a593Smuzhiyun }
508*4882a593Smuzhiyun 
509*4882a593Smuzhiyun /**
510*4882a593Smuzhiyun  * mips_cdmm_bus_discover() - Discover the devices on the CDMM bus.
511*4882a593Smuzhiyun  * @bus:	CDMM bus information, must already be set up.
512*4882a593Smuzhiyun  */
mips_cdmm_bus_discover(struct mips_cdmm_bus * bus)513*4882a593Smuzhiyun static void mips_cdmm_bus_discover(struct mips_cdmm_bus *bus)
514*4882a593Smuzhiyun {
515*4882a593Smuzhiyun 	void __iomem *cdmm;
516*4882a593Smuzhiyun 	u32 acsr;
517*4882a593Smuzhiyun 	unsigned int drb, type, size, rev;
518*4882a593Smuzhiyun 	struct mips_cdmm_device *dev;
519*4882a593Smuzhiyun 	unsigned int cpu = smp_processor_id();
520*4882a593Smuzhiyun 	int ret = 0;
521*4882a593Smuzhiyun 	int id = 0;
522*4882a593Smuzhiyun 
523*4882a593Smuzhiyun 	/* Skip the first block if it's reserved for more registers */
524*4882a593Smuzhiyun 	drb = bus->drbs_reserved;
525*4882a593Smuzhiyun 	cdmm = bus->regs;
526*4882a593Smuzhiyun 
527*4882a593Smuzhiyun 	/* Discover devices */
528*4882a593Smuzhiyun 	bus->discovered = true;
529*4882a593Smuzhiyun 	pr_info("cdmm%u discovery (%u blocks)\n", cpu, bus->drbs);
530*4882a593Smuzhiyun 	for (; drb < bus->drbs; drb += size + 1) {
531*4882a593Smuzhiyun 		acsr = __raw_readl(cdmm + drb * CDMM_DRB_SIZE);
532*4882a593Smuzhiyun 		type = (acsr & CDMM_ACSR_DEVTYPE) >> CDMM_ACSR_DEVTYPE_SHIFT;
533*4882a593Smuzhiyun 		size = (acsr & CDMM_ACSR_DEVSIZE) >> CDMM_ACSR_DEVSIZE_SHIFT;
534*4882a593Smuzhiyun 		rev  = (acsr & CDMM_ACSR_DEVREV)  >> CDMM_ACSR_DEVREV_SHIFT;
535*4882a593Smuzhiyun 
536*4882a593Smuzhiyun 		if (!type)
537*4882a593Smuzhiyun 			continue;
538*4882a593Smuzhiyun 
539*4882a593Smuzhiyun 		pr_info("cdmm%u-%u: @%u (%#x..%#x), type 0x%02x, rev %u\n",
540*4882a593Smuzhiyun 			cpu, id, drb, drb * CDMM_DRB_SIZE,
541*4882a593Smuzhiyun 			(drb + size + 1) * CDMM_DRB_SIZE - 1,
542*4882a593Smuzhiyun 			type, rev);
543*4882a593Smuzhiyun 
544*4882a593Smuzhiyun 		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
545*4882a593Smuzhiyun 		if (!dev)
546*4882a593Smuzhiyun 			break;
547*4882a593Smuzhiyun 
548*4882a593Smuzhiyun 		dev->cpu = cpu;
549*4882a593Smuzhiyun 		dev->res.start = bus->phys + drb * CDMM_DRB_SIZE;
550*4882a593Smuzhiyun 		dev->res.end = bus->phys +
551*4882a593Smuzhiyun 				(drb + size + 1) * CDMM_DRB_SIZE - 1;
552*4882a593Smuzhiyun 		dev->res.flags = IORESOURCE_MEM;
553*4882a593Smuzhiyun 		dev->type = type;
554*4882a593Smuzhiyun 		dev->rev = rev;
555*4882a593Smuzhiyun 		dev->dev.parent = get_cpu_device(cpu);
556*4882a593Smuzhiyun 		dev->dev.bus = &mips_cdmm_bustype;
557*4882a593Smuzhiyun 		dev->dev.id = atomic_inc_return(&mips_cdmm_next_id);
558*4882a593Smuzhiyun 		dev->dev.release = mips_cdmm_release;
559*4882a593Smuzhiyun 
560*4882a593Smuzhiyun 		dev_set_name(&dev->dev, "cdmm%u-%u", cpu, id);
561*4882a593Smuzhiyun 		++id;
562*4882a593Smuzhiyun 		ret = device_register(&dev->dev);
563*4882a593Smuzhiyun 		if (ret)
564*4882a593Smuzhiyun 			put_device(&dev->dev);
565*4882a593Smuzhiyun 	}
566*4882a593Smuzhiyun }
567*4882a593Smuzhiyun 
568*4882a593Smuzhiyun 
569*4882a593Smuzhiyun /*
570*4882a593Smuzhiyun  * CPU hotplug and initialisation
571*4882a593Smuzhiyun  *
572*4882a593Smuzhiyun  * All the CDMM driver callbacks need to be executed on the appropriate CPU from
573*4882a593Smuzhiyun  * workqueues. For the CPU callbacks, they need to be called for all devices on
574*4882a593Smuzhiyun  * that CPU, so the work function calls bus_for_each_dev, using a helper
575*4882a593Smuzhiyun  * (generated with BUILD_PERDEV_HELPER) to call the driver callback if the
576*4882a593Smuzhiyun  * device's CPU matches.
577*4882a593Smuzhiyun  */
578*4882a593Smuzhiyun 
579*4882a593Smuzhiyun /**
580*4882a593Smuzhiyun  * BUILD_PERDEV_HELPER() - Helper to call a CDMM driver callback if CPU matches.
581*4882a593Smuzhiyun  * @_name:	Name of CDMM driver callback function.
582*4882a593Smuzhiyun  *
583*4882a593Smuzhiyun  * Generates a bus_for_each_dev callback function to call a specific CDMM driver
584*4882a593Smuzhiyun  * callback function for the device if the device's CPU matches that pointed to
585*4882a593Smuzhiyun  * by the data argument.
586*4882a593Smuzhiyun  *
587*4882a593Smuzhiyun  * This is used for informing drivers for all devices on a given CPU of some
588*4882a593Smuzhiyun  * event (such as the CPU going online/offline).
589*4882a593Smuzhiyun  *
590*4882a593Smuzhiyun  * It is expected to already be called from the appropriate CPU.
591*4882a593Smuzhiyun  */
592*4882a593Smuzhiyun #define BUILD_PERDEV_HELPER(_name)					\
593*4882a593Smuzhiyun static int mips_cdmm_##_name##_helper(struct device *dev, void *data)	\
594*4882a593Smuzhiyun {									\
595*4882a593Smuzhiyun 	struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);	\
596*4882a593Smuzhiyun 	struct mips_cdmm_driver *cdrv;					\
597*4882a593Smuzhiyun 	unsigned int cpu = *(unsigned int *)data;			\
598*4882a593Smuzhiyun 									\
599*4882a593Smuzhiyun 	if (cdev->cpu != cpu || !dev->driver)				\
600*4882a593Smuzhiyun 		return 0;						\
601*4882a593Smuzhiyun 									\
602*4882a593Smuzhiyun 	cdrv = to_mips_cdmm_driver(dev->driver);			\
603*4882a593Smuzhiyun 	if (!cdrv->_name)						\
604*4882a593Smuzhiyun 		return 0;						\
605*4882a593Smuzhiyun 	return cdrv->_name(cdev);					\
606*4882a593Smuzhiyun }
607*4882a593Smuzhiyun 
608*4882a593Smuzhiyun /* bus_for_each_dev callback helper functions */
609*4882a593Smuzhiyun BUILD_PERDEV_HELPER(cpu_down)       /* int mips_cdmm_cpu_down_helper(...) */
BUILD_PERDEV_HELPER(cpu_up)610*4882a593Smuzhiyun BUILD_PERDEV_HELPER(cpu_up)         /* int mips_cdmm_cpu_up_helper(...) */
611*4882a593Smuzhiyun 
612*4882a593Smuzhiyun /**
613*4882a593Smuzhiyun  * mips_cdmm_cpu_down_prep() - Callback for CPUHP DOWN_PREP:
614*4882a593Smuzhiyun  *			       Tear down the CDMM bus.
615*4882a593Smuzhiyun  * @cpu:	unsigned int CPU number.
616*4882a593Smuzhiyun  *
617*4882a593Smuzhiyun  * This function is executed on the hotplugged CPU and calls the CDMM
618*4882a593Smuzhiyun  * driver cpu_down callback for all devices on that CPU.
619*4882a593Smuzhiyun  */
620*4882a593Smuzhiyun static int mips_cdmm_cpu_down_prep(unsigned int cpu)
621*4882a593Smuzhiyun {
622*4882a593Smuzhiyun 	struct mips_cdmm_bus *bus;
623*4882a593Smuzhiyun 	long ret;
624*4882a593Smuzhiyun 
625*4882a593Smuzhiyun 	/* Inform all the devices on the bus */
626*4882a593Smuzhiyun 	ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, &cpu,
627*4882a593Smuzhiyun 			       mips_cdmm_cpu_down_helper);
628*4882a593Smuzhiyun 
629*4882a593Smuzhiyun 	/*
630*4882a593Smuzhiyun 	 * While bus is offline, each use of it should reconfigure it just in
631*4882a593Smuzhiyun 	 * case it is first use when coming back online again.
632*4882a593Smuzhiyun 	 */
633*4882a593Smuzhiyun 	bus = mips_cdmm_get_bus();
634*4882a593Smuzhiyun 	if (!IS_ERR(bus))
635*4882a593Smuzhiyun 		bus->offline = true;
636*4882a593Smuzhiyun 
637*4882a593Smuzhiyun 	return ret;
638*4882a593Smuzhiyun }
639*4882a593Smuzhiyun 
640*4882a593Smuzhiyun /**
641*4882a593Smuzhiyun  * mips_cdmm_cpu_online() - Callback for CPUHP ONLINE: Bring up the CDMM bus.
642*4882a593Smuzhiyun  * @cpu:	unsigned int CPU number.
643*4882a593Smuzhiyun  *
644*4882a593Smuzhiyun  * This work_on_cpu callback function is executed on a given CPU to discover
645*4882a593Smuzhiyun  * CDMM devices on that CPU, or to call the CDMM driver cpu_up callback for all
646*4882a593Smuzhiyun  * devices already discovered on that CPU.
647*4882a593Smuzhiyun  *
648*4882a593Smuzhiyun  * It is used as work_on_cpu callback function during
649*4882a593Smuzhiyun  * initialisation. When CPUs are brought online the function is
650*4882a593Smuzhiyun  * invoked directly on the hotplugged CPU.
651*4882a593Smuzhiyun  */
mips_cdmm_cpu_online(unsigned int cpu)652*4882a593Smuzhiyun static int mips_cdmm_cpu_online(unsigned int cpu)
653*4882a593Smuzhiyun {
654*4882a593Smuzhiyun 	struct mips_cdmm_bus *bus;
655*4882a593Smuzhiyun 	long ret;
656*4882a593Smuzhiyun 
657*4882a593Smuzhiyun 	bus = mips_cdmm_get_bus();
658*4882a593Smuzhiyun 	ret = mips_cdmm_setup(bus);
659*4882a593Smuzhiyun 	if (ret)
660*4882a593Smuzhiyun 		return ret;
661*4882a593Smuzhiyun 
662*4882a593Smuzhiyun 	/* Bus now set up, so we can drop the offline flag if still set */
663*4882a593Smuzhiyun 	bus->offline = false;
664*4882a593Smuzhiyun 
665*4882a593Smuzhiyun 	if (!bus->discovered)
666*4882a593Smuzhiyun 		mips_cdmm_bus_discover(bus);
667*4882a593Smuzhiyun 	else
668*4882a593Smuzhiyun 		/* Inform all the devices on the bus */
669*4882a593Smuzhiyun 		ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, &cpu,
670*4882a593Smuzhiyun 				       mips_cdmm_cpu_up_helper);
671*4882a593Smuzhiyun 
672*4882a593Smuzhiyun 	return ret;
673*4882a593Smuzhiyun }
674*4882a593Smuzhiyun 
675*4882a593Smuzhiyun /**
676*4882a593Smuzhiyun  * mips_cdmm_init() - Initialise CDMM bus.
677*4882a593Smuzhiyun  *
678*4882a593Smuzhiyun  * Initialise CDMM bus, discover CDMM devices for online CPUs, and arrange for
679*4882a593Smuzhiyun  * hotplug notifications so the CDMM drivers can be kept up to date.
680*4882a593Smuzhiyun  */
mips_cdmm_init(void)681*4882a593Smuzhiyun static int __init mips_cdmm_init(void)
682*4882a593Smuzhiyun {
683*4882a593Smuzhiyun 	int ret;
684*4882a593Smuzhiyun 
685*4882a593Smuzhiyun 	/* Register the bus */
686*4882a593Smuzhiyun 	ret = bus_register(&mips_cdmm_bustype);
687*4882a593Smuzhiyun 	if (ret)
688*4882a593Smuzhiyun 		return ret;
689*4882a593Smuzhiyun 
690*4882a593Smuzhiyun 	/* We want to be notified about new CPUs */
691*4882a593Smuzhiyun 	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "bus/cdmm:online",
692*4882a593Smuzhiyun 				mips_cdmm_cpu_online, mips_cdmm_cpu_down_prep);
693*4882a593Smuzhiyun 	if (ret < 0)
694*4882a593Smuzhiyun 		pr_warn("cdmm: Failed to register CPU notifier\n");
695*4882a593Smuzhiyun 
696*4882a593Smuzhiyun 	return ret;
697*4882a593Smuzhiyun }
698*4882a593Smuzhiyun subsys_initcall(mips_cdmm_init);
699