drivers/nvmem/bcm-ocotp.c

   1 /*
   2  * Copyright (C) 2016 Broadcom
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation version 2.
   7  *
   8  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
   9  * kind, whether express or implied; without even the implied warranty
  10  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/delay.h>
  15 #include <linux/device.h>
  16 #include <linux/io.h>
  17 #include <linux/module.h>
  18 #include <linux/nvmem-provider.h>
  19 #include <linux/of.h>
  20 #include <linux/of_address.h>
  21 #include <linux/platform_device.h>
  22
  23 /*
  24  * # of tries for OTP Status. The time to execute a command varies. The slowest
  25  * commands are writes which also vary based on the # of bits turned on. Writing
  26  * 0xffffffff takes ~3800 us.
  27  */
  28 #define OTPC_RETRIES                 5000
  29
  30 /* Sequence to enable OTP program */
  31 #define OTPC_PROG_EN_SEQ             { 0xf, 0x4, 0x8, 0xd }
  32
  33 /* OTPC Commands */
  34 #define OTPC_CMD_READ                0x0
  35 #define OTPC_CMD_OTP_PROG_ENABLE     0x2
  36 #define OTPC_CMD_OTP_PROG_DISABLE    0x3
  37 #define OTPC_CMD_PROGRAM             0x8
  38
  39 /* OTPC Status Bits */
  40 #define OTPC_STAT_CMD_DONE           BIT(1)
  41 #define OTPC_STAT_PROG_OK            BIT(2)
  42
  43 /* OTPC register definition */
  44 #define OTPC_MODE_REG_OFFSET         0x0
  45 #define OTPC_MODE_REG_OTPC_MODE      0
  46 #define OTPC_COMMAND_OFFSET          0x4
  47 #define OTPC_COMMAND_COMMAND_WIDTH   6
  48 #define OTPC_CMD_START_OFFSET        0x8
  49 #define OTPC_CMD_START_START         0
  50 #define OTPC_CPU_STATUS_OFFSET       0xc
  51 #define OTPC_CPUADDR_REG_OFFSET      0x28
  52 #define OTPC_CPUADDR_REG_OTPC_CPU_ADDRESS_WIDTH 16
  53 #define OTPC_CPU_WRITE_REG_OFFSET    0x2c
  54
  55 #define OTPC_CMD_MASK  (BIT(OTPC_COMMAND_COMMAND_WIDTH) - 1)
  56 #define OTPC_ADDR_MASK (BIT(OTPC_CPUADDR_REG_OTPC_CPU_ADDRESS_WIDTH) - 1)
  57
  58
  59 struct otpc_map {
  60         /* in words. */
  61         u32 otpc_row_size;
  62         /* 128 bit row / 4 words support. */
  63         u16 data_r_offset[4];
  64         /* 128 bit row / 4 words support. */
  65         u16 data_w_offset[4];
  66 };
  67
  68 static struct otpc_map otp_map = {
  69         .otpc_row_size = 1,
  70         .data_r_offset = {0x10},
  71         .data_w_offset = {0x2c},
  72 };
  73
  74 static struct otpc_map otp_map_v2 = {
  75         .otpc_row_size = 2,
  76         .data_r_offset = {0x10, 0x5c},
  77         .data_w_offset = {0x2c, 0x64},
  78 };
  79
  80 struct otpc_priv {
  81         struct device       *dev;
  82         void __iomem        *base;
  83         struct otpc_map     *map;
  84         struct nvmem_config *config;
  85 };
  86
  87 static inline void set_command(void __iomem *base, u32 command)
  88 {
  89         writel(command & OTPC_CMD_MASK, base + OTPC_COMMAND_OFFSET);
  90 }
  91
  92 static inline void set_cpu_address(void __iomem *base, u32 addr)
  93 {
  94         writel(addr & OTPC_ADDR_MASK, base + OTPC_CPUADDR_REG_OFFSET);
  95 }
  96
  97 static inline void set_start_bit(void __iomem *base)
  98 {
  99         writel(1 << OTPC_CMD_START_START, base + OTPC_CMD_START_OFFSET);
 100 }
 101
 102 static inline void reset_start_bit(void __iomem *base)
 103 {
 104         writel(0, base + OTPC_CMD_START_OFFSET);
 105 }
 106
 107 static inline void write_cpu_data(void __iomem *base, u32 value)
 108 {
 109         writel(value, base + OTPC_CPU_WRITE_REG_OFFSET);
 110 }
 111
 112 static int poll_cpu_status(void __iomem *base, u32 value)
 113 {
 114         u32 status;
 115         u32 retries;
 116
 117         for (retries = 0; retries < OTPC_RETRIES; retries++) {
 118                 status = readl(base + OTPC_CPU_STATUS_OFFSET);
 119                 if (status & value)
 120                         break;
 121                 udelay(1);
 122         }
 123         if (retries == OTPC_RETRIES)
 124                 return -EAGAIN;
 125
 126         return 0;
 127 }
 128
 129 static int enable_ocotp_program(void __iomem *base)
 130 {
 131         static const u32 vals[] = OTPC_PROG_EN_SEQ;
 132         int i;
 133         int ret;
 134
 135         /* Write the magic sequence to enable programming */
 136         set_command(base, OTPC_CMD_OTP_PROG_ENABLE);
 137         for (i = 0; i < ARRAY_SIZE(vals); i++) {
 138                 write_cpu_data(base, vals[i]);
 139                 set_start_bit(base);
 140                 ret = poll_cpu_status(base, OTPC_STAT_CMD_DONE);
 141                 reset_start_bit(base);
 142                 if (ret)
 143                         return ret;
 144         }
 145
 146         return poll_cpu_status(base, OTPC_STAT_PROG_OK);
 147 }
 148
 149 static int disable_ocotp_program(void __iomem *base)
 150 {
 151         int ret;
 152
 153         set_command(base, OTPC_CMD_OTP_PROG_DISABLE);
 154         set_start_bit(base);
 155         ret = poll_cpu_status(base, OTPC_STAT_PROG_OK);
 156         reset_start_bit(base);
 157
 158         return ret;
 159 }
 160
 161 static int bcm_otpc_read(void *context, unsigned int offset, void *val,
 162         size_t bytes)
 163 {
 164         struct otpc_priv *priv = context;
 165         u32 *buf = val;
 166         u32 bytes_read;
 167         u32 address = offset / priv->config->word_size;
 168         int i, ret;
 169
 170         for (bytes_read = 0; bytes_read < bytes;) {
 171                 set_command(priv->base, OTPC_CMD_READ);
 172                 set_cpu_address(priv->base, address++);
 173                 set_start_bit(priv->base);
 174                 ret = poll_cpu_status(priv->base, OTPC_STAT_CMD_DONE);
 175                 if (ret) {
 176                         dev_err(priv->dev, "otp read error: 0x%x", ret);
 177                         return -EIO;
 178                 }
 179
 180                 for (i = 0; i < priv->map->otpc_row_size; i++) {
 181                         *buf++ = readl(priv->base +
 182                                         priv->map->data_r_offset[i]);
 183                         bytes_read += sizeof(*buf);
 184                 }
 185
 186                 reset_start_bit(priv->base);
 187         }
 188
 189         return 0;
 190 }
 191
 192 static int bcm_otpc_write(void *context, unsigned int offset, void *val,
 193         size_t bytes)
 194 {
 195         struct otpc_priv *priv = context;
 196         u32 *buf = val;
 197         u32 bytes_written;
 198         u32 address = offset / priv->config->word_size;
 199         int i, ret;
 200
 201         if (offset % priv->config->word_size)
 202                 return -EINVAL;
 203
 204         ret = enable_ocotp_program(priv->base);
 205         if (ret)
 206                 return -EIO;
 207
 208         for (bytes_written = 0; bytes_written < bytes;) {
 209                 set_command(priv->base, OTPC_CMD_PROGRAM);
 210                 set_cpu_address(priv->base, address++);
 211                 for (i = 0; i < priv->map->otpc_row_size; i++) {
 212                         writel(*buf, priv->base + priv->map->data_w_offset[i]);
 213                         buf++;
 214                         bytes_written += sizeof(*buf);
 215                 }
 216                 set_start_bit(priv->base);
 217                 ret = poll_cpu_status(priv->base, OTPC_STAT_CMD_DONE);
 218                 reset_start_bit(priv->base);
 219                 if (ret) {
 220                         dev_err(priv->dev, "otp write error: 0x%x", ret);
 221                         return -EIO;
 222                 }
 223         }
 224
 225         disable_ocotp_program(priv->base);
 226
 227         return 0;
 228 }
 229
 230 static struct nvmem_config bcm_otpc_nvmem_config = {
 231         .name = "bcm-ocotp",
 232         .read_only = false,
 233         .word_size = 4,
 234         .stride = 4,
 235         .reg_read = bcm_otpc_read,
 236         .reg_write = bcm_otpc_write,
 237 };
 238
 239 static const struct of_device_id bcm_otpc_dt_ids[] = {
 240         { .compatible = "brcm,ocotp" },
 241         { .compatible = "brcm,ocotp-v2" },
 242         { },
 243 };
 244 MODULE_DEVICE_TABLE(of, bcm_otpc_dt_ids);
 245
 246 static int bcm_otpc_probe(struct platform_device *pdev)
 247 {
 248         struct device *dev = &pdev->dev;
 249         struct device_node *dn = dev->of_node;
 250         struct resource *res;
 251         struct otpc_priv *priv;
 252         struct nvmem_device *nvmem;
 253         int err;
 254         u32 num_words;
 255
 256         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 257         if (!priv)
 258                 return -ENOMEM;
 259
 260         if (of_device_is_compatible(dev->of_node, "brcm,ocotp"))
 261                 priv->map = &otp_map;
 262         else if (of_device_is_compatible(dev->of_node, "brcm,ocotp-v2"))
 263                 priv->map = &otp_map_v2;
 264         else {
 265                 dev_err(dev, "%s otpc config map not defined\n", __func__);
 266                 return -EINVAL;
 267         }
 268
 269         /* Get OTP base address register. */
 270         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 271         priv->base = devm_ioremap_resource(dev, res);
 272         if (IS_ERR(priv->base)) {
 273                 dev_err(dev, "unable to map I/O memory\n");
 274                 return PTR_ERR(priv->base);
 275         }
 276
 277         /* Enable CPU access to OTPC. */
 278         writel(readl(priv->base + OTPC_MODE_REG_OFFSET) |
 279                 BIT(OTPC_MODE_REG_OTPC_MODE),
 280                 priv->base + OTPC_MODE_REG_OFFSET);
 281         reset_start_bit(priv->base);
 282
 283         /* Read size of memory in words. */
 284         err = of_property_read_u32(dn, "brcm,ocotp-size", &num_words);
 285         if (err) {
 286                 dev_err(dev, "size parameter not specified\n");
 287                 return -EINVAL;
 288         } else if (num_words == 0) {
 289                 dev_err(dev, "size must be > 0\n");
 290                 return -EINVAL;
 291         }
 292
 293         bcm_otpc_nvmem_config.size = 4 * num_words;
 294         bcm_otpc_nvmem_config.dev = dev;
 295         bcm_otpc_nvmem_config.priv = priv;
 296
 297         if (of_device_is_compatible(dev->of_node, "brcm,ocotp-v2")) {
 298                 bcm_otpc_nvmem_config.word_size = 8;
 299                 bcm_otpc_nvmem_config.stride = 8;
 300         }
 301
 302         priv->config = &bcm_otpc_nvmem_config;
 303
 304         nvmem = devm_nvmem_register(dev, &bcm_otpc_nvmem_config);
 305         if (IS_ERR(nvmem)) {
 306                 dev_err(dev, "error registering nvmem config\n");
 307                 return PTR_ERR(nvmem);
 308         }
 309
 310         return 0;
 311 }
 312
 313 static struct platform_driver bcm_otpc_driver = {
 314         .probe  = bcm_otpc_probe,
 315         .driver = {
 316                 .name   = "brcm-otpc",
 317                 .of_match_table = bcm_otpc_dt_ids,
 318         },
 319 };
 320 module_platform_driver(bcm_otpc_driver);
 321
 322 MODULE_DESCRIPTION("Broadcom OTPC driver");
 323 MODULE_LICENSE("GPL v2");