4 * Driver for Microchip 23k256 SPI RAM chips
6 * Copyright © 2016 Andrew Lunn <andrew@lunn.ch>
8 * This code is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
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>
24 #define MAX_CMD_SIZE 4
31 struct mchp23k256_flash {
32 struct spi_device *spi;
35 const struct mchp23_caps *caps;
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)
43 #define to_mchp23k256_flash(x) container_of(x, struct mchp23k256_flash, mtd)
45 static void mchp23k256_addr2cmd(struct mchp23k256_flash *flash,
46 unsigned int addr, u8 *cmd)
51 * Address is sent in big endian (MSB first) and we skip
52 * the first entry of the cmd array which contains the cmd
55 for (i = flash->caps->addr_width; i > 0; i--, addr >>= 8)
59 static int mchp23k256_cmdsz(struct mchp23k256_flash *flash)
61 return 1 + flash->caps->addr_width;
64 static int mchp23k256_write(struct mtd_info *mtd, loff_t to, size_t len,
65 size_t *retlen, const unsigned char *buf)
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];
72 spi_message_init(&message);
74 command[0] = MCHP23K256_CMD_WRITE;
75 mchp23k256_addr2cmd(flash, to, command);
77 transfer[0].tx_buf = command;
78 transfer[0].len = mchp23k256_cmdsz(flash);
79 spi_message_add_tail(&transfer[0], &message);
81 transfer[1].tx_buf = buf;
82 transfer[1].len = len;
83 spi_message_add_tail(&transfer[1], &message);
85 mutex_lock(&flash->lock);
87 spi_sync(flash->spi, &message);
89 if (retlen && message.actual_length > sizeof(command))
90 *retlen += message.actual_length - sizeof(command);
92 mutex_unlock(&flash->lock);
96 static int mchp23k256_read(struct mtd_info *mtd, loff_t from, size_t len,
97 size_t *retlen, unsigned char *buf)
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];
104 spi_message_init(&message);
106 memset(&transfer, 0, sizeof(transfer));
107 command[0] = MCHP23K256_CMD_READ;
108 mchp23k256_addr2cmd(flash, from, command);
110 transfer[0].tx_buf = command;
111 transfer[0].len = mchp23k256_cmdsz(flash);
112 spi_message_add_tail(&transfer[0], &message);
114 transfer[1].rx_buf = buf;
115 transfer[1].len = len;
116 spi_message_add_tail(&transfer[1], &message);
118 mutex_lock(&flash->lock);
120 spi_sync(flash->spi, &message);
122 if (retlen && message.actual_length > sizeof(command))
123 *retlen += message.actual_length - sizeof(command);
125 mutex_unlock(&flash->lock);
130 * Set the device into sequential mode. This allows read/writes to the
131 * entire SRAM in a single operation
133 static int mchp23k256_set_mode(struct spi_device *spi)
135 struct spi_transfer transfer = {};
136 struct spi_message message;
137 unsigned char command[2];
139 spi_message_init(&message);
141 command[0] = MCHP23K256_CMD_WRITE_STATUS;
142 command[1] = MCHP23K256_MODE_SEQ;
144 transfer.tx_buf = command;
145 transfer.len = sizeof(command);
146 spi_message_add_tail(&transfer, &message);
148 return spi_sync(spi, &message);
151 static const struct mchp23_caps mchp23k256_caps = {
156 static const struct mchp23_caps mchp23lcv1024_caps = {
161 static int mchp23k256_probe(struct spi_device *spi)
163 struct mchp23k256_flash *flash;
164 struct flash_platform_data *data;
167 flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
172 mutex_init(&flash->lock);
173 spi_set_drvdata(spi, flash);
175 err = mchp23k256_set_mode(spi);
179 data = dev_get_platdata(&spi->dev);
181 flash->caps = of_device_get_match_data(&spi->dev);
183 flash->caps = &mchp23k256_caps;
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;
194 err = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
195 data ? data->nr_parts : 0);
202 static int mchp23k256_remove(struct spi_device *spi)
204 struct mchp23k256_flash *flash = spi_get_drvdata(spi);
206 return mtd_device_unregister(&flash->mtd);
209 static const struct of_device_id mchp23k256_of_table[] = {
211 .compatible = "microchip,mchp23k256",
212 .data = &mchp23k256_caps,
215 .compatible = "microchip,mchp23lcv1024",
216 .data = &mchp23lcv1024_caps,
220 MODULE_DEVICE_TABLE(of, mchp23k256_of_table);
222 static struct spi_driver mchp23k256_driver = {
224 .name = "mchp23k256",
225 .of_match_table = of_match_ptr(mchp23k256_of_table),
227 .probe = mchp23k256_probe,
228 .remove = mchp23k256_remove,
231 module_spi_driver(mchp23k256_driver);
233 MODULE_DESCRIPTION("MTD SPI driver for MCHP23K256 RAM chips");
234 MODULE_AUTHOR("Andrew Lunn <andre@lunn.ch>");
235 MODULE_LICENSE("GPL v2");
236 MODULE_ALIAS("spi:mchp23k256");