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13#include <linux/device.h>
14#include <linux/module.h>
15#include <linux/mtd/mtd.h>
16#include <linux/mtd/partitions.h>
17#include <linux/mutex.h>
18#include <linux/sched.h>
19#include <linux/sizes.h>
20#include <linux/spi/flash.h>
21#include <linux/spi/spi.h>
22#include <linux/of_device.h>
23
24#define MAX_CMD_SIZE 4
25
26struct mchp23_caps {
27 u8 addr_width;
28 unsigned int size;
29};
30
31struct mchp23k256_flash {
32 struct spi_device *spi;
33 struct mutex lock;
34 struct mtd_info mtd;
35 const struct mchp23_caps *caps;
36};
37
38#define MCHP23K256_CMD_WRITE_STATUS 0x01
39#define MCHP23K256_CMD_WRITE 0x02
40#define MCHP23K256_CMD_READ 0x03
41#define MCHP23K256_MODE_SEQ BIT(6)
42
43#define to_mchp23k256_flash(x) container_of(x, struct mchp23k256_flash, mtd)
44
45static void mchp23k256_addr2cmd(struct mchp23k256_flash *flash,
46 unsigned int addr, u8 *cmd)
47{
48 int i;
49
50
51
52
53
54
55 for (i = flash->caps->addr_width; i > 0; i--, addr >>= 8)
56 cmd[i] = addr;
57}
58
59static int mchp23k256_cmdsz(struct mchp23k256_flash *flash)
60{
61 return 1 + flash->caps->addr_width;
62}
63
64static int mchp23k256_write(struct mtd_info *mtd, loff_t to, size_t len,
65 size_t *retlen, const unsigned char *buf)
66{
67 struct mchp23k256_flash *flash = to_mchp23k256_flash(mtd);
68 struct spi_transfer transfer[2] = {};
69 struct spi_message message;
70 unsigned char command[MAX_CMD_SIZE];
71
72 spi_message_init(&message);
73
74 command[0] = MCHP23K256_CMD_WRITE;
75 mchp23k256_addr2cmd(flash, to, command);
76
77 transfer[0].tx_buf = command;
78 transfer[0].len = mchp23k256_cmdsz(flash);
79 spi_message_add_tail(&transfer[0], &message);
80
81 transfer[1].tx_buf = buf;
82 transfer[1].len = len;
83 spi_message_add_tail(&transfer[1], &message);
84
85 mutex_lock(&flash->lock);
86
87 spi_sync(flash->spi, &message);
88
89 if (retlen && message.actual_length > sizeof(command))
90 *retlen += message.actual_length - sizeof(command);
91
92 mutex_unlock(&flash->lock);
93 return 0;
94}
95
96static int mchp23k256_read(struct mtd_info *mtd, loff_t from, size_t len,
97 size_t *retlen, unsigned char *buf)
98{
99 struct mchp23k256_flash *flash = to_mchp23k256_flash(mtd);
100 struct spi_transfer transfer[2] = {};
101 struct spi_message message;
102 unsigned char command[MAX_CMD_SIZE];
103
104 spi_message_init(&message);
105
106 memset(&transfer, 0, sizeof(transfer));
107 command[0] = MCHP23K256_CMD_READ;
108 mchp23k256_addr2cmd(flash, from, command);
109
110 transfer[0].tx_buf = command;
111 transfer[0].len = mchp23k256_cmdsz(flash);
112 spi_message_add_tail(&transfer[0], &message);
113
114 transfer[1].rx_buf = buf;
115 transfer[1].len = len;
116 spi_message_add_tail(&transfer[1], &message);
117
118 mutex_lock(&flash->lock);
119
120 spi_sync(flash->spi, &message);
121
122 if (retlen && message.actual_length > sizeof(command))
123 *retlen += message.actual_length - sizeof(command);
124
125 mutex_unlock(&flash->lock);
126 return 0;
127}
128
129
130
131
132
133static int mchp23k256_set_mode(struct spi_device *spi)
134{
135 struct spi_transfer transfer = {};
136 struct spi_message message;
137 unsigned char command[2];
138
139 spi_message_init(&message);
140
141 command[0] = MCHP23K256_CMD_WRITE_STATUS;
142 command[1] = MCHP23K256_MODE_SEQ;
143
144 transfer.tx_buf = command;
145 transfer.len = sizeof(command);
146 spi_message_add_tail(&transfer, &message);
147
148 return spi_sync(spi, &message);
149}
150
151static const struct mchp23_caps mchp23k256_caps = {
152 .size = SZ_32K,
153 .addr_width = 2,
154};
155
156static const struct mchp23_caps mchp23lcv1024_caps = {
157 .size = SZ_128K,
158 .addr_width = 3,
159};
160
161static int mchp23k256_probe(struct spi_device *spi)
162{
163 struct mchp23k256_flash *flash;
164 struct flash_platform_data *data;
165 int err;
166
167 flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
168 if (!flash)
169 return -ENOMEM;
170
171 flash->spi = spi;
172 mutex_init(&flash->lock);
173 spi_set_drvdata(spi, flash);
174
175 err = mchp23k256_set_mode(spi);
176 if (err)
177 return err;
178
179 data = dev_get_platdata(&spi->dev);
180
181 flash->caps = of_device_get_match_data(&spi->dev);
182 if (!flash->caps)
183 flash->caps = &mchp23k256_caps;
184
185 mtd_set_of_node(&flash->mtd, spi->dev.of_node);
186 flash->mtd.dev.parent = &spi->dev;
187 flash->mtd.type = MTD_RAM;
188 flash->mtd.flags = MTD_CAP_RAM;
189 flash->mtd.writesize = 1;
190 flash->mtd.size = flash->caps->size;
191 flash->mtd._read = mchp23k256_read;
192 flash->mtd._write = mchp23k256_write;
193
194 err = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
195 data ? data->nr_parts : 0);
196 if (err)
197 return err;
198
199 return 0;
200}
201
202static int mchp23k256_remove(struct spi_device *spi)
203{
204 struct mchp23k256_flash *flash = spi_get_drvdata(spi);
205
206 return mtd_device_unregister(&flash->mtd);
207}
208
209static const struct of_device_id mchp23k256_of_table[] = {
210 {
211 .compatible = "microchip,mchp23k256",
212 .data = &mchp23k256_caps,
213 },
214 {
215 .compatible = "microchip,mchp23lcv1024",
216 .data = &mchp23lcv1024_caps,
217 },
218 {}
219};
220MODULE_DEVICE_TABLE(of, mchp23k256_of_table);
221
222static struct spi_driver mchp23k256_driver = {
223 .driver = {
224 .name = "mchp23k256",
225 .of_match_table = of_match_ptr(mchp23k256_of_table),
226 },
227 .probe = mchp23k256_probe,
228 .remove = mchp23k256_remove,
229};
230
231module_spi_driver(mchp23k256_driver);
232
233MODULE_DESCRIPTION("MTD SPI driver for MCHP23K256 RAM chips");
234MODULE_AUTHOR("Andrew Lunn <andre@lunn.ch>");
235MODULE_LICENSE("GPL v2");
236MODULE_ALIAS("spi:mchp23k256");
237
