1 /*
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/gpio.h>
17 #include <linux/io.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/mtd/mtd.h>
21 #include <linux/mtd/map.h>
22 #include <linux/mtd/partitions.h>
23 #include <linux/mtd/physmap.h>
24 #include <linux/platform_device.h>
25 #include <linux/slab.h>
26 #include <linux/types.h>
27
28 #define pr_devinit(fmt, args...) \
29 ({ static const 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 */
43 struct 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 */
gf_set_gpios(struct async_state * state,unsigned long ofs)63 static 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 */
gf_read(struct map_info * map,unsigned long ofs)82 static 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 * The "from" region may straddle more than one window, so toggle the GPIOs for
103 * each window region before reading its data.
104 */
gf_copy_from(struct map_info * map,void * to,unsigned long from,ssize_t len)105 static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
106 {
107 struct async_state *state = gf_map_info_to_state(map);
108
109 int this_len;
110
111 while (len) {
112 if ((from % state->win_size) + len > state->win_size)
113 this_len = state->win_size - (from % state->win_size);
114 else
115 this_len = len;
116
117 gf_set_gpios(state, from);
118 memcpy_fromio(to, map->virt + (from % state->win_size),
119 this_len);
120 len -= this_len;
121 from += this_len;
122 to += this_len;
123 }
124 }
125
126 /**
127 * gf_write() - write a word at the specified offset
128 * @map: MTD map state
129 * @ofs: desired offset to write
130 */
gf_write(struct map_info * map,map_word d1,unsigned long ofs)131 static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
132 {
133 struct async_state *state = gf_map_info_to_state(map);
134 uint16_t d;
135
136 gf_set_gpios(state, ofs);
137
138 d = d1.x[0];
139 writew(d, map->virt + (ofs % state->win_size));
140 }
141
142 /**
143 * gf_copy_to() - copy a chunk of data to the flash
144 * @map: MTD map state
145 * @to: flash offset to copy to
146 * @from: memory to copy from
147 * @len: how much to copy
148 *
149 * See gf_copy_from() caveat.
150 */
gf_copy_to(struct map_info * map,unsigned long to,const void * from,ssize_t len)151 static void gf_copy_to(struct map_info *map, unsigned long to,
152 const void *from, ssize_t len)
153 {
154 struct async_state *state = gf_map_info_to_state(map);
155
156 int this_len;
157
158 while (len) {
159 if ((to % state->win_size) + len > state->win_size)
160 this_len = state->win_size - (to % state->win_size);
161 else
162 this_len = len;
163
164 gf_set_gpios(state, to);
165 memcpy_toio(map->virt + (to % state->win_size), from, len);
166
167 len -= this_len;
168 to += this_len;
169 from += this_len;
170 }
171 }
172
173 static const char * const part_probe_types[] = {
174 "cmdlinepart", "RedBoot", NULL };
175
176 /**
177 * gpio_flash_probe() - setup a mapping for a GPIO assisted flash
178 * @pdev: platform device
179 *
180 * The platform resource layout expected looks something like:
181 * struct mtd_partition partitions[] = { ... };
182 * struct physmap_flash_data flash_data = { ... };
183 * unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
184 * struct resource flash_resource[] = {
185 * {
186 * .name = "cfi_probe",
187 * .start = 0x20000000,
188 * .end = 0x201fffff,
189 * .flags = IORESOURCE_MEM,
190 * }, {
191 * .start = (unsigned long)flash_gpios,
192 * .end = ARRAY_SIZE(flash_gpios),
193 * .flags = IORESOURCE_IRQ,
194 * }
195 * };
196 * struct platform_device flash_device = {
197 * .name = "gpio-addr-flash",
198 * .dev = { .platform_data = &flash_data, },
199 * .num_resources = ARRAY_SIZE(flash_resource),
200 * .resource = flash_resource,
201 * ...
202 * };
203 */
gpio_flash_probe(struct platform_device * pdev)204 static int gpio_flash_probe(struct platform_device *pdev)
205 {
206 size_t i, arr_size;
207 struct physmap_flash_data *pdata;
208 struct resource *memory;
209 struct resource *gpios;
210 struct async_state *state;
211
212 pdata = dev_get_platdata(&pdev->dev);
213 memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
214 gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
215
216 if (!memory || !gpios || !gpios->end)
217 return -EINVAL;
218
219 arr_size = sizeof(int) * gpios->end;
220 state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
221 if (!state)
222 return -ENOMEM;
223
224 /*
225 * We cast start/end to known types in the boards file, so cast
226 * away their pointer types here to the known types (gpios->xxx).
227 */
228 state->gpio_count = gpios->end;
229 state->gpio_addrs = (void *)(unsigned long)gpios->start;
230 state->gpio_values = (void *)(state + 1);
231 state->win_size = resource_size(memory);
232 memset(state->gpio_values, 0xff, arr_size);
233
234 state->map.name = DRIVER_NAME;
235 state->map.read = gf_read;
236 state->map.copy_from = gf_copy_from;
237 state->map.write = gf_write;
238 state->map.copy_to = gf_copy_to;
239 state->map.bankwidth = pdata->width;
240 state->map.size = state->win_size * (1 << state->gpio_count);
241 state->map.virt = ioremap_nocache(memory->start, state->map.size);
242 state->map.phys = NO_XIP;
243 state->map.map_priv_1 = (unsigned long)state;
244
245 platform_set_drvdata(pdev, state);
246
247 i = 0;
248 do {
249 if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
250 pr_devinit(KERN_ERR PFX "failed to request gpio %d\n",
251 state->gpio_addrs[i]);
252 while (i--)
253 gpio_free(state->gpio_addrs[i]);
254 kfree(state);
255 return -EBUSY;
256 }
257 gpio_direction_output(state->gpio_addrs[i], 0);
258 } while (++i < state->gpio_count);
259
260 pr_devinit(KERN_NOTICE PFX "probing %d-bit flash bus\n",
261 state->map.bankwidth * 8);
262 state->mtd = do_map_probe(memory->name, &state->map);
263 if (!state->mtd) {
264 for (i = 0; i < state->gpio_count; ++i)
265 gpio_free(state->gpio_addrs[i]);
266 kfree(state);
267 return -ENXIO;
268 }
269 state->mtd->dev.parent = &pdev->dev;
270
271 mtd_device_parse_register(state->mtd, part_probe_types, NULL,
272 pdata->parts, pdata->nr_parts);
273
274 return 0;
275 }
276
gpio_flash_remove(struct platform_device * pdev)277 static int gpio_flash_remove(struct platform_device *pdev)
278 {
279 struct async_state *state = platform_get_drvdata(pdev);
280 size_t i = 0;
281 do {
282 gpio_free(state->gpio_addrs[i]);
283 } while (++i < state->gpio_count);
284 mtd_device_unregister(state->mtd);
285 map_destroy(state->mtd);
286 kfree(state);
287 return 0;
288 }
289
290 static struct platform_driver gpio_flash_driver = {
291 .probe = gpio_flash_probe,
292 .remove = gpio_flash_remove,
293 .driver = {
294 .name = DRIVER_NAME,
295 },
296 };
297
298 module_platform_driver(gpio_flash_driver);
299
300 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
301 MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
302 MODULE_LICENSE("GPL");
303