1 /* 2 * Freescale MXS On-Chip OTP driver 3 * 4 * Copyright (C) 2015 Stefan Wahren <stefan.wahren@i2se.com> 5 * 6 * Based on the driver from Huang Shijie and Christoph G. Baumann 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 */ 19 #include <linux/clk.h> 20 #include <linux/delay.h> 21 #include <linux/device.h> 22 #include <linux/err.h> 23 #include <linux/io.h> 24 #include <linux/module.h> 25 #include <linux/nvmem-provider.h> 26 #include <linux/of_device.h> 27 #include <linux/platform_device.h> 28 #include <linux/regmap.h> 29 #include <linux/slab.h> 30 #include <linux/stmp_device.h> 31 32 /* OCOTP registers and bits */ 33 34 #define BM_OCOTP_CTRL_RD_BANK_OPEN BIT(12) 35 #define BM_OCOTP_CTRL_ERROR BIT(9) 36 #define BM_OCOTP_CTRL_BUSY BIT(8) 37 38 #define OCOTP_TIMEOUT 10000 39 #define OCOTP_DATA_OFFSET 0x20 40 41 struct mxs_ocotp { 42 struct clk *clk; 43 void __iomem *base; 44 struct nvmem_device *nvmem; 45 }; 46 47 static int mxs_ocotp_wait(struct mxs_ocotp *otp) 48 { 49 int timeout = OCOTP_TIMEOUT; 50 unsigned int status = 0; 51 52 while (timeout--) { 53 status = readl(otp->base); 54 55 if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR))) 56 break; 57 58 cpu_relax(); 59 } 60 61 if (status & BM_OCOTP_CTRL_BUSY) 62 return -EBUSY; 63 else if (status & BM_OCOTP_CTRL_ERROR) 64 return -EIO; 65 66 return 0; 67 } 68 69 static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size, 70 void *val, size_t val_size) 71 { 72 struct mxs_ocotp *otp = context; 73 unsigned int offset = *(u32 *)reg; 74 u32 *buf = val; 75 int ret; 76 77 ret = clk_enable(otp->clk); 78 if (ret) 79 return ret; 80 81 writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR); 82 83 ret = mxs_ocotp_wait(otp); 84 if (ret) 85 goto disable_clk; 86 87 /* open OCOTP banks for read */ 88 writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET); 89 90 /* approximately wait 33 hclk cycles */ 91 udelay(1); 92 93 ret = mxs_ocotp_wait(otp); 94 if (ret) 95 goto close_banks; 96 97 while (val_size) { 98 if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) { 99 /* fill up non-data register */ 100 *buf = 0; 101 } else { 102 *buf = readl(otp->base + offset); 103 } 104 105 buf++; 106 val_size--; 107 offset += reg_size; 108 } 109 110 close_banks: 111 /* close banks for power saving */ 112 writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR); 113 114 disable_clk: 115 clk_disable(otp->clk); 116 117 return ret; 118 } 119 120 static int mxs_ocotp_write(void *context, const void *data, size_t count) 121 { 122 /* We don't want to support writing */ 123 return 0; 124 } 125 126 static bool mxs_ocotp_writeable_reg(struct device *dev, unsigned int reg) 127 { 128 return false; 129 } 130 131 static struct nvmem_config ocotp_config = { 132 .name = "mxs-ocotp", 133 .owner = THIS_MODULE, 134 }; 135 136 static const struct regmap_range imx23_ranges[] = { 137 regmap_reg_range(OCOTP_DATA_OFFSET, 0x210), 138 }; 139 140 static const struct regmap_access_table imx23_access = { 141 .yes_ranges = imx23_ranges, 142 .n_yes_ranges = ARRAY_SIZE(imx23_ranges), 143 }; 144 145 static const struct regmap_range imx28_ranges[] = { 146 regmap_reg_range(OCOTP_DATA_OFFSET, 0x290), 147 }; 148 149 static const struct regmap_access_table imx28_access = { 150 .yes_ranges = imx28_ranges, 151 .n_yes_ranges = ARRAY_SIZE(imx28_ranges), 152 }; 153 154 static struct regmap_bus mxs_ocotp_bus = { 155 .read = mxs_ocotp_read, 156 .write = mxs_ocotp_write, /* make regmap_init() happy */ 157 .reg_format_endian_default = REGMAP_ENDIAN_NATIVE, 158 .val_format_endian_default = REGMAP_ENDIAN_NATIVE, 159 }; 160 161 static struct regmap_config mxs_ocotp_config = { 162 .reg_bits = 32, 163 .val_bits = 32, 164 .reg_stride = 16, 165 .writeable_reg = mxs_ocotp_writeable_reg, 166 }; 167 168 static const struct of_device_id mxs_ocotp_match[] = { 169 { .compatible = "fsl,imx23-ocotp", .data = &imx23_access }, 170 { .compatible = "fsl,imx28-ocotp", .data = &imx28_access }, 171 { /* sentinel */}, 172 }; 173 MODULE_DEVICE_TABLE(of, mxs_ocotp_match); 174 175 static int mxs_ocotp_probe(struct platform_device *pdev) 176 { 177 struct device *dev = &pdev->dev; 178 struct mxs_ocotp *otp; 179 struct resource *res; 180 const struct of_device_id *match; 181 struct regmap *regmap; 182 const struct regmap_access_table *access; 183 int ret; 184 185 match = of_match_device(dev->driver->of_match_table, dev); 186 if (!match || !match->data) 187 return -EINVAL; 188 189 otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL); 190 if (!otp) 191 return -ENOMEM; 192 193 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 194 otp->base = devm_ioremap_resource(dev, res); 195 if (IS_ERR(otp->base)) 196 return PTR_ERR(otp->base); 197 198 otp->clk = devm_clk_get(&pdev->dev, NULL); 199 if (IS_ERR(otp->clk)) 200 return PTR_ERR(otp->clk); 201 202 ret = clk_prepare(otp->clk); 203 if (ret < 0) { 204 dev_err(dev, "failed to prepare clk: %d\n", ret); 205 return ret; 206 } 207 208 access = match->data; 209 mxs_ocotp_config.rd_table = access; 210 mxs_ocotp_config.max_register = access->yes_ranges[0].range_max; 211 212 regmap = devm_regmap_init(dev, &mxs_ocotp_bus, otp, &mxs_ocotp_config); 213 if (IS_ERR(regmap)) { 214 dev_err(dev, "regmap init failed\n"); 215 ret = PTR_ERR(regmap); 216 goto err_clk; 217 } 218 219 ocotp_config.dev = dev; 220 otp->nvmem = nvmem_register(&ocotp_config); 221 if (IS_ERR(otp->nvmem)) { 222 ret = PTR_ERR(otp->nvmem); 223 goto err_clk; 224 } 225 226 platform_set_drvdata(pdev, otp); 227 228 return 0; 229 230 err_clk: 231 clk_unprepare(otp->clk); 232 233 return ret; 234 } 235 236 static int mxs_ocotp_remove(struct platform_device *pdev) 237 { 238 struct mxs_ocotp *otp = platform_get_drvdata(pdev); 239 240 clk_unprepare(otp->clk); 241 242 return nvmem_unregister(otp->nvmem); 243 } 244 245 static struct platform_driver mxs_ocotp_driver = { 246 .probe = mxs_ocotp_probe, 247 .remove = mxs_ocotp_remove, 248 .driver = { 249 .name = "mxs-ocotp", 250 .of_match_table = mxs_ocotp_match, 251 }, 252 }; 253 254 module_platform_driver(mxs_ocotp_driver); 255 MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>"); 256 MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28"); 257 MODULE_LICENSE("GPL v2"); 258