drivers/nvmem/bcm-ocotp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 // Copyright (C) 2016 Broadcom
   3
   4 #include <linux/acpi.h>
   5 #include <linux/delay.h>
   6 #include <linux/device.h>
   7 #include <linux/io.h>
   8 #include <linux/module.h>
   9 #include <linux/nvmem-provider.h>
  10 #include <linux/of.h>
  11 #include <linux/platform_device.h>
  12
  13 /*
  14  * # of tries for OTP Status. The time to execute a command varies. The slowest
  15  * commands are writes which also vary based on the # of bits turned on. Writing
  16  * 0xffffffff takes ~3800 us.
  17  */
  18 #define OTPC_RETRIES                 5000
  19
  20 /* Sequence to enable OTP program */
  21 #define OTPC_PROG_EN_SEQ             { 0xf, 0x4, 0x8, 0xd }
  22
  23 /* OTPC Commands */
  24 #define OTPC_CMD_READ                0x0
  25 #define OTPC_CMD_OTP_PROG_ENABLE     0x2
  26 #define OTPC_CMD_OTP_PROG_DISABLE    0x3
  27 #define OTPC_CMD_PROGRAM             0x8
  28
  29 /* OTPC Status Bits */
  30 #define OTPC_STAT_CMD_DONE           BIT(1)
  31 #define OTPC_STAT_PROG_OK            BIT(2)
  32
  33 /* OTPC register definition */
  34 #define OTPC_MODE_REG_OFFSET         0x0
  35 #define OTPC_MODE_REG_OTPC_MODE      0
  36 #define OTPC_COMMAND_OFFSET          0x4
  37 #define OTPC_COMMAND_COMMAND_WIDTH   6
  38 #define OTPC_CMD_START_OFFSET        0x8
  39 #define OTPC_CMD_START_START         0
  40 #define OTPC_CPU_STATUS_OFFSET       0xc
  41 #define OTPC_CPUADDR_REG_OFFSET      0x28
  42 #define OTPC_CPUADDR_REG_OTPC_CPU_ADDRESS_WIDTH 16
  43 #define OTPC_CPU_WRITE_REG_OFFSET    0x2c
  44
  45 #define OTPC_CMD_MASK  (BIT(OTPC_COMMAND_COMMAND_WIDTH) - 1)
  46 #define OTPC_ADDR_MASK (BIT(OTPC_CPUADDR_REG_OTPC_CPU_ADDRESS_WIDTH) - 1)
  47
  48
  49 struct otpc_map {
  50         /* in words. */
  51         u32 otpc_row_size;
  52         /* 128 bit row / 4 words support. */
  53         u16 data_r_offset[4];
  54         /* 128 bit row / 4 words support. */
  55         u16 data_w_offset[4];
  56 };
  57
  58 static struct otpc_map otp_map = {
  59         .otpc_row_size = 1,
  60         .data_r_offset = {0x10},
  61         .data_w_offset = {0x2c},
  62 };
  63
  64 static struct otpc_map otp_map_v2 = {
  65         .otpc_row_size = 2,
  66         .data_r_offset = {0x10, 0x5c},
  67         .data_w_offset = {0x2c, 0x64},
  68 };
  69
  70 struct otpc_priv {
  71         struct device *dev;
  72         void __iomem *base;
  73         const struct otpc_map *map;
  74         struct nvmem_config *config;
  75 };
  76
  77 static inline void set_command(void __iomem *base, u32 command)
  78 {
  79         writel(command & OTPC_CMD_MASK, base + OTPC_COMMAND_OFFSET);
  80 }
  81
  82 static inline void set_cpu_address(void __iomem *base, u32 addr)
  83 {
  84         writel(addr & OTPC_ADDR_MASK, base + OTPC_CPUADDR_REG_OFFSET);
  85 }
  86
  87 static inline void set_start_bit(void __iomem *base)
  88 {
  89         writel(1 << OTPC_CMD_START_START, base + OTPC_CMD_START_OFFSET);
  90 }
  91
  92 static inline void reset_start_bit(void __iomem *base)
  93 {
  94         writel(0, base + OTPC_CMD_START_OFFSET);
  95 }
  96
  97 static inline void write_cpu_data(void __iomem *base, u32 value)
  98 {
  99         writel(value, base + OTPC_CPU_WRITE_REG_OFFSET);
 100 }
 101
 102 static int poll_cpu_status(void __iomem *base, u32 value)
 103 {
 104         u32 status;
 105         u32 retries;
 106
 107         for (retries = 0; retries < OTPC_RETRIES; retries++) {
 108                 status = readl(base + OTPC_CPU_STATUS_OFFSET);
 109                 if (status & value)
 110                         break;
 111                 udelay(1);
 112         }
 113         if (retries == OTPC_RETRIES)
 114                 return -EAGAIN;
 115
 116         return 0;
 117 }
 118
 119 static int enable_ocotp_program(void __iomem *base)
 120 {
 121         static const u32 vals[] = OTPC_PROG_EN_SEQ;
 122         int i;
 123         int ret;
 124
 125         /* Write the magic sequence to enable programming */
 126         set_command(base, OTPC_CMD_OTP_PROG_ENABLE);
 127         for (i = 0; i < ARRAY_SIZE(vals); i++) {
 128                 write_cpu_data(base, vals[i]);
 129                 set_start_bit(base);
 130                 ret = poll_cpu_status(base, OTPC_STAT_CMD_DONE);
 131                 reset_start_bit(base);
 132                 if (ret)
 133                         return ret;
 134         }
 135
 136         return poll_cpu_status(base, OTPC_STAT_PROG_OK);
 137 }
 138
 139 static int disable_ocotp_program(void __iomem *base)
 140 {
 141         int ret;
 142
 143         set_command(base, OTPC_CMD_OTP_PROG_DISABLE);
 144         set_start_bit(base);
 145         ret = poll_cpu_status(base, OTPC_STAT_PROG_OK);
 146         reset_start_bit(base);
 147
 148         return ret;
 149 }
 150
 151 static int bcm_otpc_read(void *context, unsigned int offset, void *val,
 152         size_t bytes)
 153 {
 154         struct otpc_priv *priv = context;
 155         u32 *buf = val;
 156         u32 bytes_read;
 157         u32 address = offset / priv->config->word_size;
 158         int i, ret;
 159
 160         for (bytes_read = 0; bytes_read < bytes;) {
 161                 set_command(priv->base, OTPC_CMD_READ);
 162                 set_cpu_address(priv->base, address++);
 163                 set_start_bit(priv->base);
 164                 ret = poll_cpu_status(priv->base, OTPC_STAT_CMD_DONE);
 165                 if (ret) {
 166                         dev_err(priv->dev, "otp read error: 0x%x", ret);
 167                         return -EIO;
 168                 }
 169
 170                 for (i = 0; i < priv->map->otpc_row_size; i++) {
 171                         *buf++ = readl(priv->base +
 172                                         priv->map->data_r_offset[i]);
 173                         bytes_read += sizeof(*buf);
 174                 }
 175
 176                 reset_start_bit(priv->base);
 177         }
 178
 179         return 0;
 180 }
 181
 182 static int bcm_otpc_write(void *context, unsigned int offset, void *val,
 183         size_t bytes)
 184 {
 185         struct otpc_priv *priv = context;
 186         u32 *buf = val;
 187         u32 bytes_written;
 188         u32 address = offset / priv->config->word_size;
 189         int i, ret;
 190
 191         if (offset % priv->config->word_size)
 192                 return -EINVAL;
 193
 194         ret = enable_ocotp_program(priv->base);
 195         if (ret)
 196                 return -EIO;
 197
 198         for (bytes_written = 0; bytes_written < bytes;) {
 199                 set_command(priv->base, OTPC_CMD_PROGRAM);
 200                 set_cpu_address(priv->base, address++);
 201                 for (i = 0; i < priv->map->otpc_row_size; i++) {
 202                         writel(*buf, priv->base + priv->map->data_w_offset[i]);
 203                         buf++;
 204                         bytes_written += sizeof(*buf);
 205                 }
 206                 set_start_bit(priv->base);
 207                 ret = poll_cpu_status(priv->base, OTPC_STAT_CMD_DONE);
 208                 reset_start_bit(priv->base);
 209                 if (ret) {
 210                         dev_err(priv->dev, "otp write error: 0x%x", ret);
 211                         return -EIO;
 212                 }
 213         }
 214
 215         disable_ocotp_program(priv->base);
 216
 217         return 0;
 218 }
 219
 220 static struct nvmem_config bcm_otpc_nvmem_config = {
 221         .name = "bcm-ocotp",
 222         .read_only = false,
 223         .word_size = 4,
 224         .stride = 4,
 225         .reg_read = bcm_otpc_read,
 226         .reg_write = bcm_otpc_write,
 227 };
 228
 229 static const struct of_device_id bcm_otpc_dt_ids[] = {
 230         { .compatible = "brcm,ocotp", .data = &otp_map },
 231         { .compatible = "brcm,ocotp-v2", .data = &otp_map_v2 },
 232         { },
 233 };
 234 MODULE_DEVICE_TABLE(of, bcm_otpc_dt_ids);
 235
 236 static const struct acpi_device_id bcm_otpc_acpi_ids[] __maybe_unused = {
 237         { .id = "BRCM0700", .driver_data = (kernel_ulong_t)&otp_map },
 238         { .id = "BRCM0701", .driver_data = (kernel_ulong_t)&otp_map_v2 },
 239         { /* sentinel */ }
 240 };
 241 MODULE_DEVICE_TABLE(acpi, bcm_otpc_acpi_ids);
 242
 243 static int bcm_otpc_probe(struct platform_device *pdev)
 244 {
 245         struct device *dev = &pdev->dev;
 246         struct otpc_priv *priv;
 247         struct nvmem_device *nvmem;
 248         int err;
 249         u32 num_words;
 250
 251         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 252         if (!priv)
 253                 return -ENOMEM;
 254
 255         priv->map = device_get_match_data(dev);
 256         if (!priv->map)
 257                 return -ENODEV;
 258
 259         /* Get OTP base address register. */
 260         priv->base = devm_platform_ioremap_resource(pdev, 0);
 261         if (IS_ERR(priv->base)) {
 262                 dev_err(dev, "unable to map I/O memory\n");
 263                 return PTR_ERR(priv->base);
 264         }
 265
 266         /* Enable CPU access to OTPC. */
 267         writel(readl(priv->base + OTPC_MODE_REG_OFFSET) |
 268                 BIT(OTPC_MODE_REG_OTPC_MODE),
 269                 priv->base + OTPC_MODE_REG_OFFSET);
 270         reset_start_bit(priv->base);
 271
 272         /* Read size of memory in words. */
 273         err = device_property_read_u32(dev, "brcm,ocotp-size", &num_words);
 274         if (err) {
 275                 dev_err(dev, "size parameter not specified\n");
 276                 return -EINVAL;
 277         } else if (num_words == 0) {
 278                 dev_err(dev, "size must be > 0\n");
 279                 return -EINVAL;
 280         }
 281
 282         bcm_otpc_nvmem_config.size = 4 * num_words;
 283         bcm_otpc_nvmem_config.dev = dev;
 284         bcm_otpc_nvmem_config.priv = priv;
 285
 286         if (priv->map == &otp_map_v2) {
 287                 bcm_otpc_nvmem_config.word_size = 8;
 288                 bcm_otpc_nvmem_config.stride = 8;
 289         }
 290
 291         priv->config = &bcm_otpc_nvmem_config;
 292
 293         nvmem = devm_nvmem_register(dev, &bcm_otpc_nvmem_config);
 294         if (IS_ERR(nvmem)) {
 295                 dev_err(dev, "error registering nvmem config\n");
 296                 return PTR_ERR(nvmem);
 297         }
 298
 299         return 0;
 300 }
 301
 302 static struct platform_driver bcm_otpc_driver = {
 303         .probe  = bcm_otpc_probe,
 304         .driver = {
 305                 .name   = "brcm-otpc",
 306                 .of_match_table = bcm_otpc_dt_ids,
 307                 .acpi_match_table = ACPI_PTR(bcm_otpc_acpi_ids),
 308         },
 309 };
 310 module_platform_driver(bcm_otpc_driver);
 311
 312 MODULE_DESCRIPTION("Broadcom OTPC driver");
 313 MODULE_LICENSE("GPL v2");