1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Authors:
6*4882a593Smuzhiyun * Serge Semin <Sergey.Semin@baikalelectronics.ru>
7*4882a593Smuzhiyun *
8*4882a593Smuzhiyun * Baikal-T1 Physically Mapped Internal ROM driver
9*4882a593Smuzhiyun */
10*4882a593Smuzhiyun #include <linux/bits.h>
11*4882a593Smuzhiyun #include <linux/device.h>
12*4882a593Smuzhiyun #include <linux/kernel.h>
13*4882a593Smuzhiyun #include <linux/mtd/map.h>
14*4882a593Smuzhiyun #include <linux/mtd/xip.h>
15*4882a593Smuzhiyun #include <linux/mux/consumer.h>
16*4882a593Smuzhiyun #include <linux/of.h>
17*4882a593Smuzhiyun #include <linux/of_device.h>
18*4882a593Smuzhiyun #include <linux/platform_device.h>
19*4882a593Smuzhiyun #include <linux/string.h>
20*4882a593Smuzhiyun #include <linux/types.h>
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun #include "physmap-bt1-rom.h"
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun /*
25*4882a593Smuzhiyun * Baikal-T1 SoC ROMs are only accessible by the dword-aligned instructions.
26*4882a593Smuzhiyun * We have to take this into account when implementing the data read-methods.
27*4882a593Smuzhiyun * Note there is no need in bothering with endianness, since both Baikal-T1
28*4882a593Smuzhiyun * CPU and MMIO are LE.
29*4882a593Smuzhiyun */
bt1_rom_map_read(struct map_info * map,unsigned long ofs)30*4882a593Smuzhiyun static map_word __xipram bt1_rom_map_read(struct map_info *map,
31*4882a593Smuzhiyun unsigned long ofs)
32*4882a593Smuzhiyun {
33*4882a593Smuzhiyun void __iomem *src = map->virt + ofs;
34*4882a593Smuzhiyun unsigned long shift;
35*4882a593Smuzhiyun map_word ret;
36*4882a593Smuzhiyun u32 data;
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun /* Read data within offset dword. */
39*4882a593Smuzhiyun shift = (unsigned long)src & 0x3;
40*4882a593Smuzhiyun data = readl_relaxed(src - shift);
41*4882a593Smuzhiyun if (!shift) {
42*4882a593Smuzhiyun ret.x[0] = data;
43*4882a593Smuzhiyun return ret;
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun ret.x[0] = data >> (shift * BITS_PER_BYTE);
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun /* Read data from the next dword. */
48*4882a593Smuzhiyun shift = 4 - shift;
49*4882a593Smuzhiyun if (ofs + shift >= map->size)
50*4882a593Smuzhiyun return ret;
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun data = readl_relaxed(src + shift);
53*4882a593Smuzhiyun ret.x[0] |= data << (shift * BITS_PER_BYTE);
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun return ret;
56*4882a593Smuzhiyun }
57*4882a593Smuzhiyun
bt1_rom_map_copy_from(struct map_info * map,void * to,unsigned long from,ssize_t len)58*4882a593Smuzhiyun static void __xipram bt1_rom_map_copy_from(struct map_info *map,
59*4882a593Smuzhiyun void *to, unsigned long from,
60*4882a593Smuzhiyun ssize_t len)
61*4882a593Smuzhiyun {
62*4882a593Smuzhiyun void __iomem *src = map->virt + from;
63*4882a593Smuzhiyun ssize_t shift, chunk;
64*4882a593Smuzhiyun u32 data;
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun if (len <= 0 || from >= map->size)
67*4882a593Smuzhiyun return;
68*4882a593Smuzhiyun
69*4882a593Smuzhiyun /* Make sure we don't go over the map limit. */
70*4882a593Smuzhiyun len = min_t(ssize_t, map->size - from, len);
71*4882a593Smuzhiyun
72*4882a593Smuzhiyun /*
73*4882a593Smuzhiyun * Since requested data size can be pretty big we have to implement
74*4882a593Smuzhiyun * the copy procedure as optimal as possible. That's why it's split
75*4882a593Smuzhiyun * up into the next three stages: unaligned head, aligned body,
76*4882a593Smuzhiyun * unaligned tail.
77*4882a593Smuzhiyun */
78*4882a593Smuzhiyun shift = (ssize_t)src & 0x3;
79*4882a593Smuzhiyun if (shift) {
80*4882a593Smuzhiyun chunk = min_t(ssize_t, 4 - shift, len);
81*4882a593Smuzhiyun data = readl_relaxed(src - shift);
82*4882a593Smuzhiyun memcpy(to, (char *)&data + shift, chunk);
83*4882a593Smuzhiyun src += chunk;
84*4882a593Smuzhiyun to += chunk;
85*4882a593Smuzhiyun len -= chunk;
86*4882a593Smuzhiyun }
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun while (len >= 4) {
89*4882a593Smuzhiyun data = readl_relaxed(src);
90*4882a593Smuzhiyun memcpy(to, &data, 4);
91*4882a593Smuzhiyun src += 4;
92*4882a593Smuzhiyun to += 4;
93*4882a593Smuzhiyun len -= 4;
94*4882a593Smuzhiyun }
95*4882a593Smuzhiyun
96*4882a593Smuzhiyun if (len) {
97*4882a593Smuzhiyun data = readl_relaxed(src);
98*4882a593Smuzhiyun memcpy(to, &data, len);
99*4882a593Smuzhiyun }
100*4882a593Smuzhiyun }
101*4882a593Smuzhiyun
of_flash_probe_bt1_rom(struct platform_device * pdev,struct device_node * np,struct map_info * map)102*4882a593Smuzhiyun int of_flash_probe_bt1_rom(struct platform_device *pdev,
103*4882a593Smuzhiyun struct device_node *np,
104*4882a593Smuzhiyun struct map_info *map)
105*4882a593Smuzhiyun {
106*4882a593Smuzhiyun struct device *dev = &pdev->dev;
107*4882a593Smuzhiyun
108*4882a593Smuzhiyun /* It's supposed to be read-only MTD. */
109*4882a593Smuzhiyun if (!of_device_is_compatible(np, "mtd-rom")) {
110*4882a593Smuzhiyun dev_info(dev, "No mtd-rom compatible string\n");
111*4882a593Smuzhiyun return 0;
112*4882a593Smuzhiyun }
113*4882a593Smuzhiyun
114*4882a593Smuzhiyun /* Multiplatform guard. */
115*4882a593Smuzhiyun if (!of_device_is_compatible(np, "baikal,bt1-int-rom"))
116*4882a593Smuzhiyun return 0;
117*4882a593Smuzhiyun
118*4882a593Smuzhiyun /* Sanity check the device parameters retrieved from DTB. */
119*4882a593Smuzhiyun if (map->bankwidth != 4)
120*4882a593Smuzhiyun dev_warn(dev, "Bank width is supposed to be 32 bits wide\n");
121*4882a593Smuzhiyun
122*4882a593Smuzhiyun map->read = bt1_rom_map_read;
123*4882a593Smuzhiyun map->copy_from = bt1_rom_map_copy_from;
124*4882a593Smuzhiyun
125*4882a593Smuzhiyun return 0;
126*4882a593Smuzhiyun }
127