Version:  2.0.40 2.2.26 2.4.37 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17

Linux/drivers/mtd/maps/gpio-addr-flash.c

  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  */
 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  */
 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  * 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  */
107 static 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  */
125 static 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  */
145 static void gf_copy_to(struct map_info *map, unsigned long to,
146                        const void *from, ssize_t len)
147 {
148         struct async_state *state = gf_map_info_to_state(map);
149 
150         gf_set_gpios(state, to);
151 
152         /* BUG if operation crosses the win_size */
153         BUG_ON(!((to + len) % state->win_size <= (to + len)));
154 
155         /* operation does not cross the win_size, so one shot it */
156         memcpy_toio(map->virt + (to % state->win_size), from, len);
157 }
158 
159 static const char * const part_probe_types[] = {
160         "cmdlinepart", "RedBoot", NULL };
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  */
190 static int gpio_flash_probe(struct platform_device *pdev)
191 {
192         size_t i, arr_size;
193         struct physmap_flash_data *pdata;
194         struct resource *memory;
195         struct resource *gpios;
196         struct async_state *state;
197 
198         pdata = dev_get_platdata(&pdev->dev);
199         memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
200         gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
201 
202         if (!memory || !gpios || !gpios->end)
203                 return -EINVAL;
204 
205         arr_size = sizeof(int) * gpios->end;
206         state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
207         if (!state)
208                 return -ENOMEM;
209 
210         /*
211          * We cast start/end to known types in the boards file, so cast
212          * away their pointer types here to the known types (gpios->xxx).
213          */
214         state->gpio_count     = gpios->end;
215         state->gpio_addrs     = (void *)(unsigned long)gpios->start;
216         state->gpio_values    = (void *)(state + 1);
217         state->win_size       = resource_size(memory);
218         memset(state->gpio_values, 0xff, arr_size);
219 
220         state->map.name       = DRIVER_NAME;
221         state->map.read       = gf_read;
222         state->map.copy_from  = gf_copy_from;
223         state->map.write      = gf_write;
224         state->map.copy_to    = gf_copy_to;
225         state->map.bankwidth  = pdata->width;
226         state->map.size       = state->win_size * (1 << state->gpio_count);
227         state->map.virt       = ioremap_nocache(memory->start, state->map.size);
228         state->map.phys       = NO_XIP;
229         state->map.map_priv_1 = (unsigned long)state;
230 
231         platform_set_drvdata(pdev, state);
232 
233         i = 0;
234         do {
235                 if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
236                         pr_devinit(KERN_ERR PFX "failed to request gpio %d\n",
237                                 state->gpio_addrs[i]);
238                         while (i--)
239                                 gpio_free(state->gpio_addrs[i]);
240                         kfree(state);
241                         return -EBUSY;
242                 }
243                 gpio_direction_output(state->gpio_addrs[i], 0);
244         } while (++i < state->gpio_count);
245 
246         pr_devinit(KERN_NOTICE PFX "probing %d-bit flash bus\n",
247                 state->map.bankwidth * 8);
248         state->mtd = do_map_probe(memory->name, &state->map);
249         if (!state->mtd) {
250                 for (i = 0; i < state->gpio_count; ++i)
251                         gpio_free(state->gpio_addrs[i]);
252                 kfree(state);
253                 return -ENXIO;
254         }
255 
256 
257         mtd_device_parse_register(state->mtd, part_probe_types, NULL,
258                                   pdata->parts, pdata->nr_parts);
259 
260         return 0;
261 }
262 
263 static int gpio_flash_remove(struct platform_device *pdev)
264 {
265         struct async_state *state = platform_get_drvdata(pdev);
266         size_t i = 0;
267         do {
268                 gpio_free(state->gpio_addrs[i]);
269         } while (++i < state->gpio_count);
270         mtd_device_unregister(state->mtd);
271         map_destroy(state->mtd);
272         kfree(state);
273         return 0;
274 }
275 
276 static struct platform_driver gpio_flash_driver = {
277         .probe          = gpio_flash_probe,
278         .remove         = gpio_flash_remove,
279         .driver         = {
280                 .name   = DRIVER_NAME,
281         },
282 };
283 
284 module_platform_driver(gpio_flash_driver);
285 
286 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
287 MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
288 MODULE_LICENSE("GPL");
289 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us