aboutsummaryrefslogtreecommitdiff
path: root/drivers/mtd/maps/gpio-addr-flash.c
blob: 1ec66f031c51655bb4904c985565f47fc2fc3bfe (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
/*
 * drivers/mtd/maps/gpio-addr-flash.c
 *
 * Handle the case where a flash device is mostly addressed using physical
 * line and supplemented by GPIOs.  This way you can hook up say a 8MiB flash
 * to a 2MiB memory range and use the GPIOs to select a particular range.
 *
 * Copyright © 2000 Nicolas Pitre <nico@cam.org>
 * Copyright © 2005-2009 Analog Devices Inc.
 *
 * Enter bugs at http://blackfin.uclinux.org/
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/gpio.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/physmap.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/types.h>

#define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })

#define DRIVER_NAME "gpio-addr-flash"
#define PFX DRIVER_NAME ": "

/**
 * struct async_state - keep GPIO flash state
 *	@mtd:         MTD state for this mapping
 *	@map:         MTD map state for this flash
 *	@gpio_count:  number of GPIOs used to address
 *	@gpio_addrs:  array of GPIOs to twiddle
 *	@gpio_values: cached GPIO values
 *	@win_size:    dedicated memory size (if no GPIOs)
 */
struct async_state {
	struct mtd_info *mtd;
	struct map_info map;
	size_t gpio_count;
	unsigned *gpio_addrs;
	int *gpio_values;
	unsigned long win_size;
};
#define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1)

/**
 * gf_set_gpios() - set GPIO address lines to access specified flash offset
 *	@state: GPIO flash state
 *	@ofs:   desired offset to access
 *
 * Rather than call the GPIO framework every time, cache the last-programmed
 * value.  This speeds up sequential accesses (which are by far the most common
 * type).  We rely on the GPIO framework to treat non-zero value as high so
 * that we don't have to normalize the bits.
 */
static void gf_set_gpios(struct async_state *state, unsigned long ofs)
{
	size_t i = 0;
	int value;
	ofs /= state->win_size;
	do {
		value = ofs & (1 << i);
		if (state->gpio_values[i] != value) {
			gpio_set_value(state->gpio_addrs[i], value);
			state->gpio_values[i] = value;
		}
	} while (++i < state->gpio_count);
}

/**
 * gf_read() - read a word at the specified offset
 *	@map: MTD map state
 *	@ofs: desired offset to read
 */
static map_word gf_read(struct map_info *map, unsigned long ofs)
{
	struct async_state *state = gf_map_info_to_state(map);
	uint16_t word;
	map_word test;

	gf_set_gpios(state, ofs);

	word = readw(map->virt + (ofs % state->win_size));
	test.x[0] = word;
	return test;
}

/**
 * gf_copy_from() - copy a chunk of data from the flash
 *	@map:  MTD map state
 *	@to:   memory to copy to
 *	@from: flash offset to copy from
 *	@len:  how much to copy
 *
 * We rely on the MTD layer to chunk up copies such that a single request here
 * will not cross a window size.  This allows us to only wiggle the GPIOs once
 * before falling back to a normal memcpy.  Reading the higher layer code shows
 * that this is indeed the case, but add a BUG_ON() to future proof.
 */
static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
{
	struct async_state *state = gf_map_info_to_state(map);

	gf_set_gpios(state, from);

	/* BUG if operation crosses the win_size */
	BUG_ON(!((from + len) % state->win_size <= (from + len)));

	/* operation does not cross the win_size, so one shot it */
	memcpy_fromio(to, map->virt + (from % state->win_size), len);
}

/**
 * gf_write() - write a word at the specified offset
 *	@map: MTD map state
 *	@ofs: desired offset to write
 */
static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
{
	struct async_state *state = gf_map_info_to_state(map);
	uint16_t d;

	gf_set_gpios(state, ofs);

	d = d1.x[0];
	writew(d, map->virt + (ofs % state->win_size));
}

/**
 * gf_copy_to() - copy a chunk of data to the flash
 *	@map:  MTD map state
 *	@to:   flash offset to copy to
 *	@from: memory to copy from
 *	@len:  how much to copy
 *
 * See gf_copy_from() caveat.
 */
static void gf_copy_to(struct map_info *map, unsigned long to, const void *from, ssize_t len)
{
	struct async_state *state = gf_map_info_to_state(map);

	gf_set_gpios(state, to);

	/* BUG if operation crosses the win_size */
	BUG_ON(!((to + len) % state->win_size <= (to + len)));

	/* operation does not cross the win_size, so one shot it */
	memcpy_toio(map->virt + (to % state->win_size), from, len);
}

static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };

/**
 * gpio_flash_probe() - setup a mapping for a GPIO assisted flash
 *	@pdev: platform device
 *
 * The platform resource layout expected looks something like:
 * struct mtd_partition partitions[] = { ... };
 * struct physmap_flash_data flash_data = { ... };
 * unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
 * struct resource flash_resource[] = {
 *	{
 *		.name  = "cfi_probe",
 *		.start = 0x20000000,
 *		.end   = 0x201fffff,
 *		.flags = IORESOURCE_MEM,
 *	}, {
 *		.start = (unsigned long)flash_gpios,
 *		.end   = ARRAY_SIZE(flash_gpios),
 *		.flags = IORESOURCE_IRQ,
 *	}
 * };
 * struct platform_device flash_device = {
 *	.name          = "gpio-addr-flash",
 *	.dev           = { .platform_data = &flash_data, },
 *	.num_resources = ARRAY_SIZE(flash_resource),
 *	.resource      = flash_resource,
 *	...
 * };
 */
static int __devinit gpio_flash_probe(struct platform_device *pdev)
{
	size_t i, arr_size;
	struct physmap_flash_data *pdata;
	struct resource *memory;
	struct resource *gpios;
	struct async_state *state;

	pdata = pdev->dev.platform_data;
	memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);

	if (!memory || !gpios || !gpios->end)
		return -EINVAL;

	arr_size = sizeof(int) * gpios->end;
	state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
	if (!state)
		return -ENOMEM;

	/*
	 * We cast start/end to known types in the boards file, so cast
	 * away their pointer types here to the known types (gpios->xxx).
	 */
	state->gpio_count     = gpios->end;
	state->gpio_addrs     = (void *)(unsigned long)gpios->start;
	state->gpio_values    = (void *)(state + 1);
	state->win_size       = resource_size(memory);
	memset(state->gpio_values, 0xff, arr_size);

	state->map.name       = DRIVER_NAME;
	state->map.read       = gf_read;
	state->map.copy_from  = gf_copy_from;
	state->map.write      = gf_write;
	state->map.copy_to    = gf_copy_to;
	state->map.bankwidth  = pdata->width;
	state->map.size       = state->win_size * (1 << state->gpio_count);
	state->map.virt       = ioremap_nocache(memory->start, state->map.size);
	state->map.phys       = NO_XIP;
	state->map.map_priv_1 = (unsigned long)state;

	platform_set_drvdata(pdev, state);

	i = 0;
	do {
		if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
			pr_devinit(KERN_ERR PFX "failed to request gpio %d\n",
				state->gpio_addrs[i]);
			while (i--)
				gpio_free(state->gpio_addrs[i]);
			kfree(state);
			return -EBUSY;
		}
		gpio_direction_output(state->gpio_addrs[i], 0);
	} while (++i < state->gpio_count);

	pr_devinit(KERN_NOTICE PFX "probing %d-bit flash bus\n",
		state->map.bankwidth * 8);
	state->mtd = do_map_probe(memory->name, &state->map);
	if (!state->mtd) {
		for (i = 0; i < state->gpio_count; ++i)
			gpio_free(state->gpio_addrs[i]);
		kfree(state);
		return -ENXIO;
	}


	mtd_device_parse_register(state->mtd, part_probe_types, 0,
			pdata->parts, pdata->nr_parts);

	return 0;
}

static int __devexit gpio_flash_remove(struct platform_device *pdev)
{
	struct async_state *state = platform_get_drvdata(pdev);
	size_t i = 0;
	do {
		gpio_free(state->gpio_addrs[i]);
	} while (++i < state->gpio_count);
	mtd_device_unregister(state->mtd);
	map_destroy(state->mtd);
	kfree(state);
	return 0;
}

static struct platform_driver gpio_flash_driver = {
	.probe		= gpio_flash_probe,
	.remove		= __devexit_p(gpio_flash_remove),
	.driver		= {
		.name	= DRIVER_NAME,
	},
};

static int __init gpio_flash_init(void)
{
	return platform_driver_register(&gpio_flash_driver);
}
module_init(gpio_flash_init);

static void __exit gpio_flash_exit(void)
{
	platform_driver_unregister(&gpio_flash_driver);
}
module_exit(gpio_flash_exit);

MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
MODULE_LICENSE("GPL");