drivers/mtd/devices/mchp23k256.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * mchp23k256.c
   4  *
   5  * Driver for Microchip 23k256 SPI RAM chips
   6  *
   7  * Copyright © 2016 Andrew Lunn <andrew@lunn.ch>
   8  */
   9 #include <linux/device.h>
  10 #include <linux/module.h>
  11 #include <linux/mtd/mtd.h>
  12 #include <linux/mtd/partitions.h>
  13 #include <linux/mutex.h>
  14 #include <linux/sched.h>
  15 #include <linux/sizes.h>
  16 #include <linux/spi/flash.h>
  17 #include <linux/spi/spi.h>
  18 #include <linux/of_device.h>
  19
  20 #define MAX_CMD_SIZE            4
  21
  22 struct mchp23_caps {
  23         u8 addr_width;
  24         unsigned int size;
  25 };
  26
  27 struct mchp23k256_flash {
  28         struct spi_device       *spi;
  29         struct mutex            lock;
  30         struct mtd_info         mtd;
  31         const struct mchp23_caps        *caps;
  32 };
  33
  34 #define MCHP23K256_CMD_WRITE_STATUS     0x01
  35 #define MCHP23K256_CMD_WRITE            0x02
  36 #define MCHP23K256_CMD_READ             0x03
  37 #define MCHP23K256_MODE_SEQ             BIT(6)
  38
  39 #define to_mchp23k256_flash(x) container_of(x, struct mchp23k256_flash, mtd)
  40
  41 static void mchp23k256_addr2cmd(struct mchp23k256_flash *flash,
  42                                 unsigned int addr, u8 *cmd)
  43 {
  44         int i;
  45
  46         /*
  47          * Address is sent in big endian (MSB first) and we skip
  48          * the first entry of the cmd array which contains the cmd
  49          * opcode.
  50          */
  51         for (i = flash->caps->addr_width; i > 0; i--, addr >>= 8)
  52                 cmd[i] = addr;
  53 }
  54
  55 static int mchp23k256_cmdsz(struct mchp23k256_flash *flash)
  56 {
  57         return 1 + flash->caps->addr_width;
  58 }
  59
  60 static int mchp23k256_write(struct mtd_info *mtd, loff_t to, size_t len,
  61                             size_t *retlen, const unsigned char *buf)
  62 {
  63         struct mchp23k256_flash *flash = to_mchp23k256_flash(mtd);
  64         struct spi_transfer transfer[2] = {};
  65         struct spi_message message;
  66         unsigned char command[MAX_CMD_SIZE];
  67         int ret, cmd_len;
  68
  69         spi_message_init(&message);
  70
  71         cmd_len = mchp23k256_cmdsz(flash);
  72
  73         command[0] = MCHP23K256_CMD_WRITE;
  74         mchp23k256_addr2cmd(flash, to, command);
  75
  76         transfer[0].tx_buf = command;
  77         transfer[0].len = cmd_len;
  78         spi_message_add_tail(&transfer[0], &message);
  79
  80         transfer[1].tx_buf = buf;
  81         transfer[1].len = len;
  82         spi_message_add_tail(&transfer[1], &message);
  83
  84         mutex_lock(&flash->lock);
  85
  86         ret = spi_sync(flash->spi, &message);
  87
  88         mutex_unlock(&flash->lock);
  89
  90         if (ret)
  91                 return ret;
  92
  93         if (retlen && message.actual_length > cmd_len)
  94                 *retlen += message.actual_length - cmd_len;
  95
  96         return 0;
  97 }
  98
  99 static int mchp23k256_read(struct mtd_info *mtd, loff_t from, size_t len,
 100                            size_t *retlen, unsigned char *buf)
 101 {
 102         struct mchp23k256_flash *flash = to_mchp23k256_flash(mtd);
 103         struct spi_transfer transfer[2] = {};
 104         struct spi_message message;
 105         unsigned char command[MAX_CMD_SIZE];
 106         int ret, cmd_len;
 107
 108         spi_message_init(&message);
 109
 110         cmd_len = mchp23k256_cmdsz(flash);
 111
 112         memset(&transfer, 0, sizeof(transfer));
 113         command[0] = MCHP23K256_CMD_READ;
 114         mchp23k256_addr2cmd(flash, from, command);
 115
 116         transfer[0].tx_buf = command;
 117         transfer[0].len = cmd_len;
 118         spi_message_add_tail(&transfer[0], &message);
 119
 120         transfer[1].rx_buf = buf;
 121         transfer[1].len = len;
 122         spi_message_add_tail(&transfer[1], &message);
 123
 124         mutex_lock(&flash->lock);
 125
 126         ret = spi_sync(flash->spi, &message);
 127
 128         mutex_unlock(&flash->lock);
 129
 130         if (ret)
 131                 return ret;
 132
 133         if (retlen && message.actual_length > cmd_len)
 134                 *retlen += message.actual_length - cmd_len;
 135
 136         return 0;
 137 }
 138
 139 /*
 140  * Set the device into sequential mode. This allows read/writes to the
 141  * entire SRAM in a single operation
 142  */
 143 static int mchp23k256_set_mode(struct spi_device *spi)
 144 {
 145         struct spi_transfer transfer = {};
 146         struct spi_message message;
 147         unsigned char command[2];
 148
 149         spi_message_init(&message);
 150
 151         command[0] = MCHP23K256_CMD_WRITE_STATUS;
 152         command[1] = MCHP23K256_MODE_SEQ;
 153
 154         transfer.tx_buf = command;
 155         transfer.len = sizeof(command);
 156         spi_message_add_tail(&transfer, &message);
 157
 158         return spi_sync(spi, &message);
 159 }
 160
 161 static const struct mchp23_caps mchp23k256_caps = {
 162         .size = SZ_32K,
 163         .addr_width = 2,
 164 };
 165
 166 static const struct mchp23_caps mchp23lcv1024_caps = {
 167         .size = SZ_128K,
 168         .addr_width = 3,
 169 };
 170
 171 static int mchp23k256_probe(struct spi_device *spi)
 172 {
 173         struct mchp23k256_flash *flash;
 174         struct flash_platform_data *data;
 175         int err;
 176
 177         flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
 178         if (!flash)
 179                 return -ENOMEM;
 180
 181         flash->spi = spi;
 182         mutex_init(&flash->lock);
 183         spi_set_drvdata(spi, flash);
 184
 185         err = mchp23k256_set_mode(spi);
 186         if (err)
 187                 return err;
 188
 189         data = dev_get_platdata(&spi->dev);
 190
 191         flash->caps = of_device_get_match_data(&spi->dev);
 192         if (!flash->caps)
 193                 flash->caps = &mchp23k256_caps;
 194
 195         mtd_set_of_node(&flash->mtd, spi->dev.of_node);
 196         flash->mtd.dev.parent   = &spi->dev;
 197         flash->mtd.type         = MTD_RAM;
 198         flash->mtd.flags        = MTD_CAP_RAM;
 199         flash->mtd.writesize    = 1;
 200         flash->mtd.size         = flash->caps->size;
 201         flash->mtd._read        = mchp23k256_read;
 202         flash->mtd._write       = mchp23k256_write;
 203
 204         err = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
 205                                   data ? data->nr_parts : 0);
 206         if (err)
 207                 return err;
 208
 209         return 0;
 210 }
 211
 212 static int mchp23k256_remove(struct spi_device *spi)
 213 {
 214         struct mchp23k256_flash *flash = spi_get_drvdata(spi);
 215
 216         return mtd_device_unregister(&flash->mtd);
 217 }
 218
 219 static const struct of_device_id mchp23k256_of_table[] = {
 220         {
 221                 .compatible = "microchip,mchp23k256",
 222                 .data = &mchp23k256_caps,
 223         },
 224         {
 225                 .compatible = "microchip,mchp23lcv1024",
 226                 .data = &mchp23lcv1024_caps,
 227         },
 228         {}
 229 };
 230 MODULE_DEVICE_TABLE(of, mchp23k256_of_table);
 231
 232 static struct spi_driver mchp23k256_driver = {
 233         .driver = {
 234                 .name   = "mchp23k256",
 235                 .of_match_table = of_match_ptr(mchp23k256_of_table),
 236         },
 237         .probe          = mchp23k256_probe,
 238         .remove         = mchp23k256_remove,
 239 };
 240
 241 module_spi_driver(mchp23k256_driver);
 242
 243 MODULE_DESCRIPTION("MTD SPI driver for MCHP23K256 RAM chips");
 244 MODULE_AUTHOR("Andrew Lunn <andre@lunn.ch>");
 245 MODULE_LICENSE("GPL v2");
 246 MODULE_ALIAS("spi:mchp23k256");