1 /*
2 * Copyright (c) 2017 Intel Corporation
3 *
4 * Intel Mobile Internet Devices (MID) based on Intel Atom SoCs have few
5 * microcontrollers inside to do some auxiliary tasks. One of such
6 * microcontroller is System Controller Unit (SCU) which, in particular,
7 * is servicing watchdog and controlling system reset function.
8 *
9 * This driver enables IPC channel to SCU.
10 *
11 * SPDX-License-Identifier: GPL-2.0+
12 */
13 #include <common.h>
14 #include <dm.h>
15 #include <regmap.h>
16 #include <syscon.h>
17 #include <asm/cpu.h>
18 #include <asm/scu.h>
19 #include <linux/errno.h>
20 #include <linux/io.h>
21 #include <linux/kernel.h>
22
23 /* SCU register map */
24 struct ipc_regs {
25 u32 cmd;
26 u32 status;
27 u32 sptr;
28 u32 dptr;
29 u32 reserved[28];
30 u32 wbuf[4];
31 u32 rbuf[4];
32 };
33
34 struct scu {
35 struct ipc_regs *regs;
36 };
37
38 /**
39 * scu_ipc_send_command() - send command to SCU
40 * @regs: register map of SCU
41 * @cmd: command
42 *
43 * Command Register (Write Only):
44 * A write to this register results in an interrupt to the SCU core processor
45 * Format:
46 * |rfu2(8) | size(8) | command id(4) | rfu1(3) | ioc(1) | command(8)|
47 */
scu_ipc_send_command(struct ipc_regs * regs,u32 cmd)48 static void scu_ipc_send_command(struct ipc_regs *regs, u32 cmd)
49 {
50 writel(cmd, ®s->cmd);
51 }
52
53 /**
54 * scu_ipc_check_status() - check status of last command
55 * @regs: register map of SCU
56 *
57 * Status Register (Read Only):
58 * Driver will read this register to get the ready/busy status of the IPC
59 * block and error status of the IPC command that was just processed by SCU
60 * Format:
61 * |rfu3(8)|error code(8)|initiator id(8)|cmd id(4)|rfu1(2)|error(1)|busy(1)|
62 */
scu_ipc_check_status(struct ipc_regs * regs)63 static int scu_ipc_check_status(struct ipc_regs *regs)
64 {
65 int loop_count = 100000;
66 int status;
67
68 do {
69 status = readl(®s->status);
70 if (!(status & BIT(0)))
71 break;
72
73 udelay(1);
74 } while (--loop_count);
75 if (!loop_count)
76 return -ETIMEDOUT;
77
78 if (status & BIT(1)) {
79 printf("%s() status=0x%08x\n", __func__, status);
80 return -EIO;
81 }
82
83 return 0;
84 }
85
scu_ipc_cmd(struct ipc_regs * regs,u32 cmd,u32 sub,u32 * in,int inlen,u32 * out,int outlen)86 static int scu_ipc_cmd(struct ipc_regs *regs, u32 cmd, u32 sub,
87 u32 *in, int inlen, u32 *out, int outlen)
88 {
89 int i, err;
90
91 for (i = 0; i < inlen; i++)
92 writel(*in++, ®s->wbuf[i]);
93
94 scu_ipc_send_command(regs, (inlen << 16) | (sub << 12) | cmd);
95 err = scu_ipc_check_status(regs);
96
97 if (!err) {
98 for (i = 0; i < outlen; i++)
99 *out++ = readl(®s->rbuf[i]);
100 }
101
102 return err;
103 }
104
105 /**
106 * scu_ipc_simple_command() - send a simple command
107 * @cmd: command
108 * @sub: sub type
109 *
110 * Issue a simple command to the SCU. Do not use this interface if
111 * you must then access data as any data values may be overwritten
112 * by another SCU access by the time this function returns.
113 *
114 * This function may sleep. Locking for SCU accesses is handled for
115 * the caller.
116 */
scu_ipc_simple_command(u32 cmd,u32 sub)117 int scu_ipc_simple_command(u32 cmd, u32 sub)
118 {
119 struct scu *scu;
120 struct udevice *dev;
121 int ret;
122
123 ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev);
124 if (ret)
125 return ret;
126
127 scu = dev_get_priv(dev);
128
129 scu_ipc_send_command(scu->regs, sub << 12 | cmd);
130 return scu_ipc_check_status(scu->regs);
131 }
132
scu_ipc_command(u32 cmd,u32 sub,u32 * in,int inlen,u32 * out,int outlen)133 int scu_ipc_command(u32 cmd, u32 sub, u32 *in, int inlen, u32 *out, int outlen)
134 {
135 struct scu *scu;
136 struct udevice *dev;
137 int ret;
138
139 ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev);
140 if (ret)
141 return ret;
142
143 scu = dev_get_priv(dev);
144
145 return scu_ipc_cmd(scu->regs, cmd, sub, in, inlen, out, outlen);
146 }
147
scu_ipc_probe(struct udevice * dev)148 static int scu_ipc_probe(struct udevice *dev)
149 {
150 struct scu *scu = dev_get_priv(dev);
151
152 scu->regs = syscon_get_first_range(X86_SYSCON_SCU);
153
154 return 0;
155 }
156
157 static const struct udevice_id scu_ipc_match[] = {
158 { .compatible = "intel,scu-ipc", .data = X86_SYSCON_SCU },
159 { /* sentinel */ }
160 };
161
162 U_BOOT_DRIVER(scu_ipc) = {
163 .name = "scu_ipc",
164 .id = UCLASS_SYSCON,
165 .of_match = scu_ipc_match,
166 .probe = scu_ipc_probe,
167 .priv_auto_alloc_size = sizeof(struct scu),
168 };
169