1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com> 4 */ 5 6 #include <linux/clk.h> 7 #include <linux/i2c.h> 8 #include <linux/interrupt.h> 9 #include <linux/io.h> 10 #include <linux/module.h> 11 #include <linux/platform_device.h> 12 13 #define UNIPHIER_I2C_DTRM 0x00 /* TX register */ 14 #define UNIPHIER_I2C_DTRM_IRQEN BIT(11) /* enable interrupt */ 15 #define UNIPHIER_I2C_DTRM_STA BIT(10) /* start condition */ 16 #define UNIPHIER_I2C_DTRM_STO BIT(9) /* stop condition */ 17 #define UNIPHIER_I2C_DTRM_NACK BIT(8) /* do not return ACK */ 18 #define UNIPHIER_I2C_DTRM_RD BIT(0) /* read transaction */ 19 #define UNIPHIER_I2C_DREC 0x04 /* RX register */ 20 #define UNIPHIER_I2C_DREC_MST BIT(14) /* 1 = master, 0 = slave */ 21 #define UNIPHIER_I2C_DREC_TX BIT(13) /* 1 = transmit, 0 = receive */ 22 #define UNIPHIER_I2C_DREC_STS BIT(12) /* stop condition detected */ 23 #define UNIPHIER_I2C_DREC_LRB BIT(11) /* no ACK */ 24 #define UNIPHIER_I2C_DREC_LAB BIT(9) /* arbitration lost */ 25 #define UNIPHIER_I2C_DREC_BBN BIT(8) /* bus not busy */ 26 #define UNIPHIER_I2C_MYAD 0x08 /* slave address */ 27 #define UNIPHIER_I2C_CLK 0x0c /* clock frequency control */ 28 #define UNIPHIER_I2C_BRST 0x10 /* bus reset */ 29 #define UNIPHIER_I2C_BRST_FOEN BIT(1) /* normal operation */ 30 #define UNIPHIER_I2C_BRST_RSCL BIT(0) /* release SCL */ 31 #define UNIPHIER_I2C_HOLD 0x14 /* hold time control */ 32 #define UNIPHIER_I2C_BSTS 0x18 /* bus status monitor */ 33 #define UNIPHIER_I2C_BSTS_SDA BIT(1) /* readback of SDA line */ 34 #define UNIPHIER_I2C_BSTS_SCL BIT(0) /* readback of SCL line */ 35 #define UNIPHIER_I2C_NOISE 0x1c /* noise filter control */ 36 #define UNIPHIER_I2C_SETUP 0x20 /* setup time control */ 37 38 struct uniphier_i2c_priv { 39 struct completion comp; 40 struct i2c_adapter adap; 41 void __iomem *membase; 42 struct clk *clk; 43 unsigned int busy_cnt; 44 unsigned int clk_cycle; 45 }; 46 47 static irqreturn_t uniphier_i2c_interrupt(int irq, void *dev_id) 48 { 49 struct uniphier_i2c_priv *priv = dev_id; 50 51 /* 52 * This hardware uses edge triggered interrupt. Do not touch the 53 * hardware registers in this handler to make sure to catch the next 54 * interrupt edge. Just send a complete signal and return. 55 */ 56 complete(&priv->comp); 57 58 return IRQ_HANDLED; 59 } 60 61 static int uniphier_i2c_xfer_byte(struct i2c_adapter *adap, u32 txdata, 62 u32 *rxdatap) 63 { 64 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap); 65 unsigned long time_left; 66 u32 rxdata; 67 68 reinit_completion(&priv->comp); 69 70 txdata |= UNIPHIER_I2C_DTRM_IRQEN; 71 writel(txdata, priv->membase + UNIPHIER_I2C_DTRM); 72 73 time_left = wait_for_completion_timeout(&priv->comp, adap->timeout); 74 if (unlikely(!time_left)) 75 return -ETIMEDOUT; 76 77 rxdata = readl(priv->membase + UNIPHIER_I2C_DREC); 78 if (rxdatap) 79 *rxdatap = rxdata; 80 81 return 0; 82 } 83 84 static int uniphier_i2c_send_byte(struct i2c_adapter *adap, u32 txdata) 85 { 86 u32 rxdata; 87 int ret; 88 89 ret = uniphier_i2c_xfer_byte(adap, txdata, &rxdata); 90 if (ret) 91 return ret; 92 93 if (unlikely(rxdata & UNIPHIER_I2C_DREC_LAB)) 94 return -EAGAIN; 95 96 if (unlikely(rxdata & UNIPHIER_I2C_DREC_LRB)) 97 return -ENXIO; 98 99 return 0; 100 } 101 102 static int uniphier_i2c_tx(struct i2c_adapter *adap, u16 addr, u16 len, 103 const u8 *buf) 104 { 105 int ret; 106 107 ret = uniphier_i2c_send_byte(adap, addr << 1 | 108 UNIPHIER_I2C_DTRM_STA | 109 UNIPHIER_I2C_DTRM_NACK); 110 if (ret) 111 return ret; 112 113 while (len--) { 114 ret = uniphier_i2c_send_byte(adap, 115 UNIPHIER_I2C_DTRM_NACK | *buf++); 116 if (ret) 117 return ret; 118 } 119 120 return 0; 121 } 122 123 static int uniphier_i2c_rx(struct i2c_adapter *adap, u16 addr, u16 len, 124 u8 *buf) 125 { 126 int ret; 127 128 ret = uniphier_i2c_send_byte(adap, addr << 1 | 129 UNIPHIER_I2C_DTRM_STA | 130 UNIPHIER_I2C_DTRM_NACK | 131 UNIPHIER_I2C_DTRM_RD); 132 if (ret) 133 return ret; 134 135 while (len--) { 136 u32 rxdata; 137 138 ret = uniphier_i2c_xfer_byte(adap, 139 len ? 0 : UNIPHIER_I2C_DTRM_NACK, 140 &rxdata); 141 if (ret) 142 return ret; 143 *buf++ = rxdata; 144 } 145 146 return 0; 147 } 148 149 static int uniphier_i2c_stop(struct i2c_adapter *adap) 150 { 151 return uniphier_i2c_send_byte(adap, UNIPHIER_I2C_DTRM_STO | 152 UNIPHIER_I2C_DTRM_NACK); 153 } 154 155 static int uniphier_i2c_master_xfer_one(struct i2c_adapter *adap, 156 struct i2c_msg *msg, bool stop) 157 { 158 bool is_read = msg->flags & I2C_M_RD; 159 bool recovery = false; 160 int ret; 161 162 if (is_read) 163 ret = uniphier_i2c_rx(adap, msg->addr, msg->len, msg->buf); 164 else 165 ret = uniphier_i2c_tx(adap, msg->addr, msg->len, msg->buf); 166 167 if (ret == -EAGAIN) /* could not acquire bus. bail out without STOP */ 168 return ret; 169 170 if (ret == -ETIMEDOUT) { 171 /* This error is fatal. Needs recovery. */ 172 stop = false; 173 recovery = true; 174 } 175 176 if (stop) { 177 int ret2 = uniphier_i2c_stop(adap); 178 179 if (ret2) { 180 /* Failed to issue STOP. The bus needs recovery. */ 181 recovery = true; 182 ret = ret ?: ret2; 183 } 184 } 185 186 if (recovery) 187 i2c_recover_bus(adap); 188 189 return ret; 190 } 191 192 static int uniphier_i2c_check_bus_busy(struct i2c_adapter *adap) 193 { 194 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap); 195 196 if (!(readl(priv->membase + UNIPHIER_I2C_DREC) & 197 UNIPHIER_I2C_DREC_BBN)) { 198 if (priv->busy_cnt++ > 3) { 199 /* 200 * If bus busy continues too long, it is probably 201 * in a wrong state. Try bus recovery. 202 */ 203 i2c_recover_bus(adap); 204 priv->busy_cnt = 0; 205 } 206 207 return -EAGAIN; 208 } 209 210 priv->busy_cnt = 0; 211 return 0; 212 } 213 214 static int uniphier_i2c_master_xfer(struct i2c_adapter *adap, 215 struct i2c_msg *msgs, int num) 216 { 217 struct i2c_msg *msg, *emsg = msgs + num; 218 int ret; 219 220 ret = uniphier_i2c_check_bus_busy(adap); 221 if (ret) 222 return ret; 223 224 for (msg = msgs; msg < emsg; msg++) { 225 /* Emit STOP if it is the last message or I2C_M_STOP is set. */ 226 bool stop = (msg + 1 == emsg) || (msg->flags & I2C_M_STOP); 227 228 ret = uniphier_i2c_master_xfer_one(adap, msg, stop); 229 if (ret) 230 return ret; 231 } 232 233 return num; 234 } 235 236 static u32 uniphier_i2c_functionality(struct i2c_adapter *adap) 237 { 238 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 239 } 240 241 static const struct i2c_algorithm uniphier_i2c_algo = { 242 .master_xfer = uniphier_i2c_master_xfer, 243 .functionality = uniphier_i2c_functionality, 244 }; 245 246 static void uniphier_i2c_reset(struct uniphier_i2c_priv *priv, bool reset_on) 247 { 248 u32 val = UNIPHIER_I2C_BRST_RSCL; 249 250 val |= reset_on ? 0 : UNIPHIER_I2C_BRST_FOEN; 251 writel(val, priv->membase + UNIPHIER_I2C_BRST); 252 } 253 254 static int uniphier_i2c_get_scl(struct i2c_adapter *adap) 255 { 256 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap); 257 258 return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) & 259 UNIPHIER_I2C_BSTS_SCL); 260 } 261 262 static void uniphier_i2c_set_scl(struct i2c_adapter *adap, int val) 263 { 264 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap); 265 266 writel(val ? UNIPHIER_I2C_BRST_RSCL : 0, 267 priv->membase + UNIPHIER_I2C_BRST); 268 } 269 270 static int uniphier_i2c_get_sda(struct i2c_adapter *adap) 271 { 272 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap); 273 274 return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) & 275 UNIPHIER_I2C_BSTS_SDA); 276 } 277 278 static void uniphier_i2c_unprepare_recovery(struct i2c_adapter *adap) 279 { 280 uniphier_i2c_reset(i2c_get_adapdata(adap), false); 281 } 282 283 static struct i2c_bus_recovery_info uniphier_i2c_bus_recovery_info = { 284 .recover_bus = i2c_generic_scl_recovery, 285 .get_scl = uniphier_i2c_get_scl, 286 .set_scl = uniphier_i2c_set_scl, 287 .get_sda = uniphier_i2c_get_sda, 288 .unprepare_recovery = uniphier_i2c_unprepare_recovery, 289 }; 290 291 static void uniphier_i2c_hw_init(struct uniphier_i2c_priv *priv) 292 { 293 unsigned int cyc = priv->clk_cycle; 294 295 uniphier_i2c_reset(priv, true); 296 297 /* 298 * Bit30-16: clock cycles of tLOW. 299 * Standard-mode: tLOW = 4.7 us, tHIGH = 4.0 us 300 * Fast-mode: tLOW = 1.3 us, tHIGH = 0.6 us 301 * "tLow/tHIGH = 5/4" meets both. 302 */ 303 writel((cyc * 5 / 9 << 16) | cyc, priv->membase + UNIPHIER_I2C_CLK); 304 305 uniphier_i2c_reset(priv, false); 306 } 307 308 static int uniphier_i2c_probe(struct platform_device *pdev) 309 { 310 struct device *dev = &pdev->dev; 311 struct uniphier_i2c_priv *priv; 312 u32 bus_speed; 313 unsigned long clk_rate; 314 int irq, ret; 315 316 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 317 if (!priv) 318 return -ENOMEM; 319 320 priv->membase = devm_platform_ioremap_resource(pdev, 0); 321 if (IS_ERR(priv->membase)) 322 return PTR_ERR(priv->membase); 323 324 irq = platform_get_irq(pdev, 0); 325 if (irq < 0) 326 return irq; 327 328 if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed)) 329 bus_speed = I2C_MAX_STANDARD_MODE_FREQ; 330 331 if (!bus_speed || bus_speed > I2C_MAX_FAST_MODE_FREQ) { 332 dev_err(dev, "invalid clock-frequency %d\n", bus_speed); 333 return -EINVAL; 334 } 335 336 priv->clk = devm_clk_get_enabled(dev, NULL); 337 if (IS_ERR(priv->clk)) { 338 dev_err(dev, "failed to enable clock\n"); 339 return PTR_ERR(priv->clk); 340 } 341 342 clk_rate = clk_get_rate(priv->clk); 343 if (!clk_rate) { 344 dev_err(dev, "input clock rate should not be zero\n"); 345 return -EINVAL; 346 } 347 348 priv->clk_cycle = clk_rate / bus_speed; 349 init_completion(&priv->comp); 350 priv->adap.owner = THIS_MODULE; 351 priv->adap.algo = &uniphier_i2c_algo; 352 priv->adap.dev.parent = dev; 353 priv->adap.dev.of_node = dev->of_node; 354 strscpy(priv->adap.name, "UniPhier I2C", sizeof(priv->adap.name)); 355 priv->adap.bus_recovery_info = &uniphier_i2c_bus_recovery_info; 356 i2c_set_adapdata(&priv->adap, priv); 357 platform_set_drvdata(pdev, priv); 358 359 uniphier_i2c_hw_init(priv); 360 361 ret = devm_request_irq(dev, irq, uniphier_i2c_interrupt, 0, pdev->name, 362 priv); 363 if (ret) { 364 dev_err(dev, "failed to request irq %d\n", irq); 365 return ret; 366 } 367 368 return i2c_add_adapter(&priv->adap); 369 } 370 371 static void uniphier_i2c_remove(struct platform_device *pdev) 372 { 373 struct uniphier_i2c_priv *priv = platform_get_drvdata(pdev); 374 375 i2c_del_adapter(&priv->adap); 376 } 377 378 static int __maybe_unused uniphier_i2c_suspend(struct device *dev) 379 { 380 struct uniphier_i2c_priv *priv = dev_get_drvdata(dev); 381 382 clk_disable_unprepare(priv->clk); 383 384 return 0; 385 } 386 387 static int __maybe_unused uniphier_i2c_resume(struct device *dev) 388 { 389 struct uniphier_i2c_priv *priv = dev_get_drvdata(dev); 390 int ret; 391 392 ret = clk_prepare_enable(priv->clk); 393 if (ret) 394 return ret; 395 396 uniphier_i2c_hw_init(priv); 397 398 return 0; 399 } 400 401 static const struct dev_pm_ops uniphier_i2c_pm_ops = { 402 SET_SYSTEM_SLEEP_PM_OPS(uniphier_i2c_suspend, uniphier_i2c_resume) 403 }; 404 405 static const struct of_device_id uniphier_i2c_match[] = { 406 { .compatible = "socionext,uniphier-i2c" }, 407 { /* sentinel */ } 408 }; 409 MODULE_DEVICE_TABLE(of, uniphier_i2c_match); 410 411 static struct platform_driver uniphier_i2c_drv = { 412 .probe = uniphier_i2c_probe, 413 .remove_new = uniphier_i2c_remove, 414 .driver = { 415 .name = "uniphier-i2c", 416 .of_match_table = uniphier_i2c_match, 417 .pm = &uniphier_i2c_pm_ops, 418 }, 419 }; 420 module_platform_driver(uniphier_i2c_drv); 421 422 MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>"); 423 MODULE_DESCRIPTION("UniPhier I2C bus driver"); 424 MODULE_LICENSE("GPL"); 425