1 /* 2 * Freescale i.MX28 OCOTP Driver 3 * 4 * Copyright (C) 2014 Marek Vasut <marex@denx.de> 5 * 6 * SPDX-License-Identifier: GPL-2.0+ 7 * 8 * Note: The i.MX23/i.MX28 OCOTP block is a predecessor to the OCOTP block 9 * used in i.MX6 . While these blocks are very similar at the first 10 * glance, by digging deeper, one will notice differences (like the 11 * tight dependence on MXS power block, some completely new registers 12 * etc.) which would make common driver an ifdef nightmare :-( 13 */ 14 15 #include <common.h> 16 #include <fuse.h> 17 #include <linux/errno.h> 18 #include <asm/io.h> 19 #include <asm/arch/clock.h> 20 #include <asm/arch/imx-regs.h> 21 #include <asm/arch/sys_proto.h> 22 23 #define MXS_OCOTP_TIMEOUT 100000 24 25 static struct mxs_ocotp_regs *ocotp_regs = 26 (struct mxs_ocotp_regs *)MXS_OCOTP_BASE; 27 static struct mxs_power_regs *power_regs = 28 (struct mxs_power_regs *)MXS_POWER_BASE; 29 static struct mxs_clkctrl_regs *clkctrl_regs = 30 (struct mxs_clkctrl_regs *)MXS_CLKCTRL_BASE; 31 32 static int mxs_ocotp_wait_busy_clear(void) 33 { 34 uint32_t reg; 35 int timeout = MXS_OCOTP_TIMEOUT; 36 37 while (--timeout) { 38 reg = readl(&ocotp_regs->hw_ocotp_ctrl); 39 if (!(reg & OCOTP_CTRL_BUSY)) 40 break; 41 udelay(10); 42 } 43 44 if (!timeout) 45 return -EINVAL; 46 47 /* Wait a little as per FSL datasheet's 'write postamble' section. */ 48 udelay(10); 49 50 return 0; 51 } 52 53 static void mxs_ocotp_clear_error(void) 54 { 55 writel(OCOTP_CTRL_ERROR, &ocotp_regs->hw_ocotp_ctrl_clr); 56 } 57 58 static int mxs_ocotp_read_bank_open(bool open) 59 { 60 int ret = 0; 61 62 if (open) { 63 writel(OCOTP_CTRL_RD_BANK_OPEN, 64 &ocotp_regs->hw_ocotp_ctrl_set); 65 66 /* 67 * Wait before polling the BUSY bit, since the BUSY bit might 68 * be asserted only after a few HCLK cycles and if we were to 69 * poll immediatelly, we could miss the busy bit. 70 */ 71 udelay(10); 72 ret = mxs_ocotp_wait_busy_clear(); 73 } else { 74 writel(OCOTP_CTRL_RD_BANK_OPEN, 75 &ocotp_regs->hw_ocotp_ctrl_clr); 76 } 77 78 return ret; 79 } 80 81 static void mxs_ocotp_scale_vddio(bool enter, uint32_t *val) 82 { 83 uint32_t scale_val; 84 85 if (enter) { 86 /* 87 * Enter the fuse programming VDDIO voltage setup. We start 88 * scaling the voltage from it's current value down to 2.8V 89 * which is the one and only correct voltage for programming 90 * the OCOTP fuses (according to datasheet). 91 */ 92 scale_val = readl(&power_regs->hw_power_vddioctrl); 93 scale_val &= POWER_VDDIOCTRL_TRG_MASK; 94 95 /* Return the original voltage. */ 96 *val = scale_val; 97 98 /* 99 * Start scaling VDDIO down to 0x2, which is 2.8V . Actually, 100 * the value 0x0 should be 2.8V, but that's not the case on 101 * most designs due to load etc., so we play safe. Undervolt 102 * can actually cause incorrect programming of the fuses and 103 * or reboots of the board. 104 */ 105 while (scale_val > 2) { 106 clrsetbits_le32(&power_regs->hw_power_vddioctrl, 107 POWER_VDDIOCTRL_TRG_MASK, --scale_val); 108 udelay(500); 109 } 110 } else { 111 /* Start scaling VDDIO up to original value . */ 112 for (scale_val = 2; scale_val <= *val; scale_val++) { 113 clrsetbits_le32(&power_regs->hw_power_vddioctrl, 114 POWER_VDDIOCTRL_TRG_MASK, scale_val); 115 udelay(500); 116 } 117 } 118 119 mdelay(10); 120 } 121 122 static int mxs_ocotp_wait_hclk_ready(void) 123 { 124 uint32_t reg, timeout = MXS_OCOTP_TIMEOUT; 125 126 while (--timeout) { 127 reg = readl(&clkctrl_regs->hw_clkctrl_hbus); 128 if (!(reg & CLKCTRL_HBUS_ASM_BUSY)) 129 break; 130 } 131 132 if (!timeout) 133 return -EINVAL; 134 135 return 0; 136 } 137 138 static int mxs_ocotp_scale_hclk(bool enter, uint32_t *val) 139 { 140 uint32_t scale_val; 141 int ret; 142 143 ret = mxs_ocotp_wait_hclk_ready(); 144 if (ret) 145 return ret; 146 147 /* Set CPU bypass */ 148 writel(CLKCTRL_CLKSEQ_BYPASS_CPU, 149 &clkctrl_regs->hw_clkctrl_clkseq_set); 150 151 if (enter) { 152 /* Return the original HCLK clock speed. */ 153 *val = readl(&clkctrl_regs->hw_clkctrl_hbus); 154 *val &= CLKCTRL_HBUS_DIV_MASK; 155 *val >>= CLKCTRL_HBUS_DIV_OFFSET; 156 157 /* Scale the HCLK to 454/19 = 23.9 MHz . */ 158 scale_val = (~19) << CLKCTRL_HBUS_DIV_OFFSET; 159 scale_val &= CLKCTRL_HBUS_DIV_MASK; 160 } else { 161 /* Scale the HCLK back to original frequency. */ 162 scale_val = (~(*val)) << CLKCTRL_HBUS_DIV_OFFSET; 163 scale_val &= CLKCTRL_HBUS_DIV_MASK; 164 } 165 166 writel(CLKCTRL_HBUS_DIV_MASK, 167 &clkctrl_regs->hw_clkctrl_hbus_set); 168 writel(scale_val, 169 &clkctrl_regs->hw_clkctrl_hbus_clr); 170 171 mdelay(10); 172 173 ret = mxs_ocotp_wait_hclk_ready(); 174 if (ret) 175 return ret; 176 177 /* Disable CPU bypass */ 178 writel(CLKCTRL_CLKSEQ_BYPASS_CPU, 179 &clkctrl_regs->hw_clkctrl_clkseq_clr); 180 181 mdelay(10); 182 183 return 0; 184 } 185 186 static int mxs_ocotp_write_fuse(uint32_t addr, uint32_t mask) 187 { 188 uint32_t hclk_val, vddio_val; 189 int ret; 190 191 mxs_ocotp_clear_error(); 192 193 /* Make sure the banks are closed for reading. */ 194 ret = mxs_ocotp_read_bank_open(0); 195 if (ret) { 196 puts("Failed closing banks for reading!\n"); 197 return ret; 198 } 199 200 ret = mxs_ocotp_scale_hclk(1, &hclk_val); 201 if (ret) { 202 puts("Failed scaling down the HCLK!\n"); 203 return ret; 204 } 205 mxs_ocotp_scale_vddio(1, &vddio_val); 206 207 ret = mxs_ocotp_wait_busy_clear(); 208 if (ret) { 209 puts("Failed waiting for ready state!\n"); 210 goto fail; 211 } 212 213 /* Program the fuse address */ 214 writel(addr | OCOTP_CTRL_WR_UNLOCK_KEY, &ocotp_regs->hw_ocotp_ctrl); 215 216 /* Program the data. */ 217 writel(mask, &ocotp_regs->hw_ocotp_data); 218 219 udelay(10); 220 221 ret = mxs_ocotp_wait_busy_clear(); 222 if (ret) { 223 puts("Failed waiting for ready state!\n"); 224 goto fail; 225 } 226 227 /* Check for errors */ 228 if (readl(&ocotp_regs->hw_ocotp_ctrl) & OCOTP_CTRL_ERROR) { 229 puts("Failed writing fuses!\n"); 230 ret = -EPERM; 231 goto fail; 232 } 233 234 fail: 235 mxs_ocotp_scale_vddio(0, &vddio_val); 236 if (mxs_ocotp_scale_hclk(0, &hclk_val)) 237 puts("Failed scaling up the HCLK!\n"); 238 239 return ret; 240 } 241 242 static int mxs_ocotp_read_fuse(uint32_t reg, uint32_t *val) 243 { 244 int ret; 245 246 /* Register offset from CUST0 */ 247 reg = ((uint32_t)&ocotp_regs->hw_ocotp_cust0) + (reg << 4); 248 249 ret = mxs_ocotp_wait_busy_clear(); 250 if (ret) { 251 puts("Failed waiting for ready state!\n"); 252 return ret; 253 } 254 255 mxs_ocotp_clear_error(); 256 257 ret = mxs_ocotp_read_bank_open(1); 258 if (ret) { 259 puts("Failed opening banks for reading!\n"); 260 return ret; 261 } 262 263 *val = readl(reg); 264 265 ret = mxs_ocotp_read_bank_open(0); 266 if (ret) { 267 puts("Failed closing banks for reading!\n"); 268 return ret; 269 } 270 271 return ret; 272 } 273 274 static int mxs_ocotp_valid(u32 bank, u32 word) 275 { 276 if (bank > 4) 277 return -EINVAL; 278 if (word > 7) 279 return -EINVAL; 280 return 0; 281 } 282 283 /* 284 * The 'fuse' command API 285 */ 286 int fuse_read(u32 bank, u32 word, u32 *val) 287 { 288 int ret; 289 290 ret = mxs_ocotp_valid(bank, word); 291 if (ret) 292 return ret; 293 294 return mxs_ocotp_read_fuse((bank << 3) | word, val); 295 } 296 297 int fuse_prog(u32 bank, u32 word, u32 val) 298 { 299 int ret; 300 301 ret = mxs_ocotp_valid(bank, word); 302 if (ret) 303 return ret; 304 305 return mxs_ocotp_write_fuse((bank << 3) | word, val); 306 } 307 308 int fuse_sense(u32 bank, u32 word, u32 *val) 309 { 310 /* We do not support sensing :-( */ 311 return -EINVAL; 312 } 313 314 int fuse_override(u32 bank, u32 word, u32 val) 315 { 316 /* We do not support overriding :-( */ 317 return -EINVAL; 318 } 319