blob: 44ef9a49a8609b62fc184c254b6fe53b6a618332 [file] [log] [blame]
Mike Frysingerd79c3262009-05-20 12:04:09 -04001/*
2 * drivers/mtd/maps/gpio-addr-flash.c
3 *
4 * Handle the case where a flash device is mostly addressed using physical
5 * line and supplemented by GPIOs. This way you can hook up say a 8MiB flash
6 * to a 2MiB memory range and use the GPIOs to select a particular range.
7 *
8 * Copyright © 2000 Nicolas Pitre <nico@cam.org>
9 * Copyright © 2005-2009 Analog Devices Inc.
10 *
11 * Enter bugs at http://blackfin.uclinux.org/
12 *
13 * Licensed under the GPL-2 or later.
14 */
15
16#include <linux/init.h>
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/mtd/mtd.h>
20#include <linux/mtd/map.h>
21#include <linux/mtd/partitions.h>
22#include <linux/mtd/physmap.h>
23#include <linux/platform_device.h>
24#include <linux/types.h>
25
26#include <asm/gpio.h>
27#include <asm/io.h>
28
29#define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })
30
31#define DRIVER_NAME "gpio-addr-flash"
32#define PFX DRIVER_NAME ": "
33
34/**
35 * struct async_state - keep GPIO flash state
36 * @mtd: MTD state for this mapping
37 * @map: MTD map state for this flash
38 * @gpio_count: number of GPIOs used to address
39 * @gpio_addrs: array of GPIOs to twiddle
40 * @gpio_values: cached GPIO values
41 * @win_size: dedicated memory size (if no GPIOs)
42 */
43struct async_state {
44 struct mtd_info *mtd;
45 struct map_info map;
46 size_t gpio_count;
47 unsigned *gpio_addrs;
48 int *gpio_values;
49 unsigned long win_size;
50};
51#define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1)
52
53/**
54 * gf_set_gpios() - set GPIO address lines to access specified flash offset
55 * @state: GPIO flash state
56 * @ofs: desired offset to access
57 *
58 * Rather than call the GPIO framework every time, cache the last-programmed
59 * value. This speeds up sequential accesses (which are by far the most common
60 * type). We rely on the GPIO framework to treat non-zero value as high so
61 * that we don't have to normalize the bits.
62 */
63static void gf_set_gpios(struct async_state *state, unsigned long ofs)
64{
65 size_t i = 0;
66 int value;
67 ofs /= state->win_size;
68 do {
69 value = ofs & (1 << i);
70 if (state->gpio_values[i] != value) {
71 gpio_set_value(state->gpio_addrs[i], value);
72 state->gpio_values[i] = value;
73 }
74 } while (++i < state->gpio_count);
75}
76
77/**
78 * gf_read() - read a word at the specified offset
79 * @map: MTD map state
80 * @ofs: desired offset to read
81 */
82static map_word gf_read(struct map_info *map, unsigned long ofs)
83{
84 struct async_state *state = gf_map_info_to_state(map);
85 uint16_t word;
86 map_word test;
87
88 gf_set_gpios(state, ofs);
89
90 word = readw(map->virt + (ofs % state->win_size));
91 test.x[0] = word;
92 return test;
93}
94
95/**
96 * gf_copy_from() - copy a chunk of data from the flash
97 * @map: MTD map state
98 * @to: memory to copy to
99 * @from: flash offset to copy from
100 * @len: how much to copy
101 *
102 * We rely on the MTD layer to chunk up copies such that a single request here
103 * will not cross a window size. This allows us to only wiggle the GPIOs once
104 * before falling back to a normal memcpy. Reading the higher layer code shows
105 * that this is indeed the case, but add a BUG_ON() to future proof.
106 */
107static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
108{
109 struct async_state *state = gf_map_info_to_state(map);
110
111 gf_set_gpios(state, from);
112
113 /* BUG if operation crosses the win_size */
114 BUG_ON(!((from + len) % state->win_size <= (from + len)));
115
116 /* operation does not cross the win_size, so one shot it */
117 memcpy_fromio(to, map->virt + (from % state->win_size), len);
118}
119
120/**
121 * gf_write() - write a word at the specified offset
122 * @map: MTD map state
123 * @ofs: desired offset to write
124 */
125static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
126{
127 struct async_state *state = gf_map_info_to_state(map);
128 uint16_t d;
129
130 gf_set_gpios(state, ofs);
131
132 d = d1.x[0];
133 writew(d, map->virt + (ofs % state->win_size));
134}
135
136/**
137 * gf_copy_to() - copy a chunk of data to the flash
138 * @map: MTD map state
139 * @to: flash offset to copy to
140 * @from: memory to copy from
141 * @len: how much to copy
142 *
143 * See gf_copy_from() caveat.
144 */
145static void gf_copy_to(struct map_info *map, unsigned long to, const void *from, ssize_t len)
146{
147 struct async_state *state = gf_map_info_to_state(map);
148
149 gf_set_gpios(state, to);
150
151 /* BUG if operation crosses the win_size */
152 BUG_ON(!((to + len) % state->win_size <= (to + len)));
153
154 /* operation does not cross the win_size, so one shot it */
155 memcpy_toio(map->virt + (to % state->win_size), from, len);
156}
157
158#ifdef CONFIG_MTD_PARTITIONS
159static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };
160#endif
161
162/**
163 * gpio_flash_probe() - setup a mapping for a GPIO assisted flash
164 * @pdev: platform device
165 *
166 * The platform resource layout expected looks something like:
167 * struct mtd_partition partitions[] = { ... };
168 * struct physmap_flash_data flash_data = { ... };
169 * unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
170 * struct resource flash_resource[] = {
171 * {
172 * .name = "cfi_probe",
173 * .start = 0x20000000,
174 * .end = 0x201fffff,
175 * .flags = IORESOURCE_MEM,
176 * }, {
177 * .start = (unsigned long)flash_gpios,
178 * .end = ARRAY_SIZE(flash_gpios),
179 * .flags = IORESOURCE_IRQ,
180 * }
181 * };
182 * struct platform_device flash_device = {
183 * .name = "gpio-addr-flash",
184 * .dev = { .platform_data = &flash_data, },
185 * .num_resources = ARRAY_SIZE(flash_resource),
186 * .resource = flash_resource,
187 * ...
188 * };
189 */
190static int __devinit gpio_flash_probe(struct platform_device *pdev)
191{
192 int ret;
193 size_t i, arr_size;
194 struct physmap_flash_data *pdata;
195 struct resource *memory;
196 struct resource *gpios;
197 struct async_state *state;
198
199 pdata = pdev->dev.platform_data;
200 memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
201 gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
202
203 if (!memory || !gpios || !gpios->end)
204 return -EINVAL;
205
206 arr_size = sizeof(int) * gpios->end;
207 state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
208 if (!state)
209 return -ENOMEM;
210
211 state->gpio_count = gpios->end;
212 state->gpio_addrs = (void *)gpios->start;
213 state->gpio_values = (void *)(state + 1);
214 state->win_size = memory->end - memory->start + 1;
215 memset(state->gpio_values, 0xff, arr_size);
216
217 state->map.name = DRIVER_NAME;
218 state->map.read = gf_read;
219 state->map.copy_from = gf_copy_from;
220 state->map.write = gf_write;
221 state->map.copy_to = gf_copy_to;
222 state->map.bankwidth = pdata->width;
223 state->map.size = state->win_size * (1 << state->gpio_count);
224 state->map.virt = (void __iomem *)memory->start;
225 state->map.phys = NO_XIP;
226 state->map.map_priv_1 = (unsigned long)state;
227
228 platform_set_drvdata(pdev, state);
229
230 i = 0;
231 do {
232 if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
233 pr_devinit(KERN_ERR PFX "failed to request gpio %d\n",
234 state->gpio_addrs[i]);
235 while (i--)
236 gpio_free(state->gpio_addrs[i]);
237 kfree(state);
238 return -EBUSY;
239 }
240 gpio_direction_output(state->gpio_addrs[i], 0);
241 } while (++i < state->gpio_count);
242
243 pr_devinit(KERN_NOTICE PFX "probing %d-bit flash bus\n",
244 state->map.bankwidth * 8);
245 state->mtd = do_map_probe(memory->name, &state->map);
246 if (!state->mtd) {
247 for (i = 0; i < state->gpio_count; ++i)
248 gpio_free(state->gpio_addrs[i]);
249 kfree(state);
250 return -ENXIO;
251 }
252
253#ifdef CONFIG_MTD_PARTITIONS
254 ret = parse_mtd_partitions(state->mtd, part_probe_types, &pdata->parts, 0);
255 if (ret > 0) {
256 pr_devinit(KERN_NOTICE PFX "Using commandline partition definition\n");
257 add_mtd_partitions(state->mtd, pdata->parts, ret);
258 kfree(pdata->parts);
259
260 } else if (pdata->nr_parts) {
261 pr_devinit(KERN_NOTICE PFX "Using board partition definition\n");
262 add_mtd_partitions(state->mtd, pdata->parts, pdata->nr_parts);
263
264 } else
265#endif
266 {
267 pr_devinit(KERN_NOTICE PFX "no partition info available, registering whole flash at once\n");
268 add_mtd_device(state->mtd);
269 }
270
271 return 0;
272}
273
274static int __devexit gpio_flash_remove(struct platform_device *pdev)
275{
276 struct async_state *state = platform_get_drvdata(pdev);
277 size_t i = 0;
278 do {
279 gpio_free(state->gpio_addrs[i]);
280 } while (++i < state->gpio_count);
281#ifdef CONFIG_MTD_PARTITIONS
282 del_mtd_partitions(state->mtd);
283#endif
284 map_destroy(state->mtd);
285 kfree(state);
286 return 0;
287}
288
289static struct platform_driver gpio_flash_driver = {
290 .probe = gpio_flash_probe,
291 .remove = __devexit_p(gpio_flash_remove),
292 .driver = {
293 .name = DRIVER_NAME,
294 },
295};
296
297static int __init gpio_flash_init(void)
298{
299 return platform_driver_register(&gpio_flash_driver);
300}
301module_init(gpio_flash_init);
302
303static void __exit gpio_flash_exit(void)
304{
305 platform_driver_unregister(&gpio_flash_driver);
306}
307module_exit(gpio_flash_exit);
308
309MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
310MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
311MODULE_LICENSE("GPL");