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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * I2C bus driver for Kontron COM modules4 *5 * Copyright (c) 2010-2013 Kontron Europe GmbH6 * Author: Michael Brunner <michael.brunner@kontron.com>7 *8 * The driver is based on the i2c-ocores driver by Peter Korsgaard.9 */10 11#include <linux/module.h>12#include <linux/platform_device.h>13#include <linux/i2c.h>14#include <linux/delay.h>15#include <linux/mfd/kempld.h>16 17#define KEMPLD_I2C_PRELOW 0x0b18#define KEMPLD_I2C_PREHIGH 0x0c19#define KEMPLD_I2C_DATA 0x0e20 21#define KEMPLD_I2C_CTRL 0x0d22#define I2C_CTRL_IEN 0x4023#define I2C_CTRL_EN 0x8024 25#define KEMPLD_I2C_STAT 0x0f26#define I2C_STAT_IF 0x0127#define I2C_STAT_TIP 0x0228#define I2C_STAT_ARBLOST 0x2029#define I2C_STAT_BUSY 0x4030#define I2C_STAT_NACK 0x8031 32#define KEMPLD_I2C_CMD 0x0f33#define I2C_CMD_START 0x9134#define I2C_CMD_STOP 0x4135#define I2C_CMD_READ 0x2136#define I2C_CMD_WRITE 0x1137#define I2C_CMD_READ_ACK 0x2138#define I2C_CMD_READ_NACK 0x2939#define I2C_CMD_IACK 0x0140 41#define KEMPLD_I2C_FREQ_MAX 2700 /* 2.7 mHz */42#define KEMPLD_I2C_FREQ_STD 100 /* 100 kHz */43 44enum {45 STATE_DONE = 0,46 STATE_INIT,47 STATE_ADDR,48 STATE_ADDR10,49 STATE_START,50 STATE_WRITE,51 STATE_READ,52 STATE_ERROR,53};54 55struct kempld_i2c_data {56 struct device *dev;57 struct kempld_device_data *pld;58 struct i2c_adapter adap;59 struct i2c_msg *msg;60 int pos;61 int nmsgs;62 int state;63 bool was_active;64};65 66static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;67module_param(bus_frequency, uint, 0);68MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="69 __MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");70 71static int i2c_bus = -1;72module_param(i2c_bus, int, 0);73MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");74 75static bool i2c_gpio_mux;76module_param(i2c_gpio_mux, bool, 0);77MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");78 79/*80 * kempld_get_mutex must be called prior to calling this function.81 */82static int kempld_i2c_process(struct kempld_i2c_data *i2c)83{84 struct kempld_device_data *pld = i2c->pld;85 u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);86 struct i2c_msg *msg = i2c->msg;87 u8 addr;88 89 /* Ready? */90 if (stat & I2C_STAT_TIP)91 return -EBUSY;92 93 if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {94 /* Stop has been sent */95 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);96 if (i2c->state == STATE_ERROR)97 return -EIO;98 return 0;99 }100 101 /* Error? */102 if (stat & I2C_STAT_ARBLOST) {103 i2c->state = STATE_ERROR;104 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);105 return -EAGAIN;106 }107 108 if (i2c->state == STATE_INIT) {109 if (stat & I2C_STAT_BUSY)110 return -EBUSY;111 112 i2c->state = STATE_ADDR;113 }114 115 if (i2c->state == STATE_ADDR) {116 /* 10 bit address? */117 if (i2c->msg->flags & I2C_M_TEN) {118 addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);119 /* Set read bit if necessary */120 addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;121 i2c->state = STATE_ADDR10;122 } else {123 addr = i2c_8bit_addr_from_msg(i2c->msg);124 i2c->state = STATE_START;125 }126 127 kempld_write8(pld, KEMPLD_I2C_DATA, addr);128 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);129 130 return 0;131 }132 133 /* Second part of 10 bit addressing */134 if (i2c->state == STATE_ADDR10) {135 kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);136 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);137 138 i2c->state = STATE_START;139 return 0;140 }141 142 if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {143 i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;144 145 if (stat & I2C_STAT_NACK) {146 i2c->state = STATE_ERROR;147 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);148 return -ENXIO;149 }150 } else {151 msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);152 }153 154 if (i2c->pos >= msg->len) {155 i2c->nmsgs--;156 i2c->msg++;157 i2c->pos = 0;158 msg = i2c->msg;159 160 if (i2c->nmsgs) {161 if (!(msg->flags & I2C_M_NOSTART)) {162 i2c->state = STATE_ADDR;163 return 0;164 } else {165 i2c->state = (msg->flags & I2C_M_RD)166 ? STATE_READ : STATE_WRITE;167 }168 } else {169 i2c->state = STATE_DONE;170 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);171 return 0;172 }173 }174 175 if (i2c->state == STATE_READ) {176 kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?177 I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);178 } else {179 kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);180 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);181 }182 183 return 0;184}185 186static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,187 int num)188{189 struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);190 struct kempld_device_data *pld = i2c->pld;191 unsigned long timeout = jiffies + HZ;192 int ret;193 194 i2c->msg = msgs;195 i2c->pos = 0;196 i2c->nmsgs = num;197 i2c->state = STATE_INIT;198 199 /* Handle the transfer */200 while (time_before(jiffies, timeout)) {201 kempld_get_mutex(pld);202 ret = kempld_i2c_process(i2c);203 kempld_release_mutex(pld);204 205 if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)206 return (i2c->state == STATE_DONE) ? num : ret;207 208 if (ret == 0)209 timeout = jiffies + HZ;210 211 usleep_range(5, 15);212 }213 214 i2c->state = STATE_ERROR;215 216 return -ETIMEDOUT;217}218 219/*220 * kempld_get_mutex must be called prior to calling this function.221 */222static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)223{224 struct kempld_device_data *pld = i2c->pld;225 u16 prescale_corr;226 long prescale;227 u8 ctrl;228 u8 stat;229 u8 cfg;230 231 /* Make sure the device is disabled */232 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);233 ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);234 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);235 236 if (bus_frequency > KEMPLD_I2C_FREQ_MAX)237 bus_frequency = KEMPLD_I2C_FREQ_MAX;238 239 if (pld->info.spec_major == 1)240 prescale = pld->pld_clock / (bus_frequency * 5) - 1000;241 else242 prescale = pld->pld_clock / (bus_frequency * 4) - 3000;243 244 if (prescale < 0)245 prescale = 0;246 247 /* Round to the best matching value */248 prescale_corr = prescale / 1000;249 if (prescale % 1000 >= 500)250 prescale_corr++;251 252 kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);253 kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);254 255 /* Activate I2C bus output on GPIO pins */256 cfg = kempld_read8(pld, KEMPLD_CFG);257 if (i2c_gpio_mux)258 cfg |= KEMPLD_CFG_GPIO_I2C_MUX;259 else260 cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;261 kempld_write8(pld, KEMPLD_CFG, cfg);262 263 /* Enable the device */264 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);265 ctrl |= I2C_CTRL_EN;266 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);267 268 stat = kempld_read8(pld, KEMPLD_I2C_STAT);269 if (stat & I2C_STAT_BUSY)270 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);271}272 273static u32 kempld_i2c_func(struct i2c_adapter *adap)274{275 return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;276}277 278static const struct i2c_algorithm kempld_i2c_algorithm = {279 .xfer = kempld_i2c_xfer,280 .functionality = kempld_i2c_func,281};282 283static const struct i2c_adapter kempld_i2c_adapter = {284 .owner = THIS_MODULE,285 .name = "i2c-kempld",286 .class = I2C_CLASS_HWMON | I2C_CLASS_DEPRECATED,287 .algo = &kempld_i2c_algorithm,288};289 290static int kempld_i2c_probe(struct platform_device *pdev)291{292 struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);293 struct kempld_i2c_data *i2c;294 int ret;295 u8 ctrl;296 297 i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);298 if (!i2c)299 return -ENOMEM;300 301 i2c->pld = pld;302 i2c->dev = &pdev->dev;303 i2c->adap = kempld_i2c_adapter;304 i2c->adap.dev.parent = i2c->dev;305 ACPI_COMPANION_SET(&i2c->adap.dev, ACPI_COMPANION(&pdev->dev));306 i2c_set_adapdata(&i2c->adap, i2c);307 platform_set_drvdata(pdev, i2c);308 309 kempld_get_mutex(pld);310 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);311 312 if (ctrl & I2C_CTRL_EN)313 i2c->was_active = true;314 315 kempld_i2c_device_init(i2c);316 kempld_release_mutex(pld);317 318 /* Add I2C adapter to I2C tree */319 if (i2c_bus >= -1)320 i2c->adap.nr = i2c_bus;321 ret = i2c_add_numbered_adapter(&i2c->adap);322 if (ret)323 return ret;324 325 dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",326 bus_frequency);327 328 return 0;329}330 331static void kempld_i2c_remove(struct platform_device *pdev)332{333 struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);334 struct kempld_device_data *pld = i2c->pld;335 u8 ctrl;336 337 kempld_get_mutex(pld);338 /*339 * Disable I2C logic if it was not activated before the340 * driver loaded341 */342 if (!i2c->was_active) {343 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);344 ctrl &= ~I2C_CTRL_EN;345 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);346 }347 kempld_release_mutex(pld);348 349 i2c_del_adapter(&i2c->adap);350}351 352static int kempld_i2c_suspend(struct device *dev)353{354 struct kempld_i2c_data *i2c = dev_get_drvdata(dev);355 struct kempld_device_data *pld = i2c->pld;356 u8 ctrl;357 358 kempld_get_mutex(pld);359 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);360 ctrl &= ~I2C_CTRL_EN;361 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);362 kempld_release_mutex(pld);363 364 return 0;365}366 367static int kempld_i2c_resume(struct device *dev)368{369 struct kempld_i2c_data *i2c = dev_get_drvdata(dev);370 struct kempld_device_data *pld = i2c->pld;371 372 kempld_get_mutex(pld);373 kempld_i2c_device_init(i2c);374 kempld_release_mutex(pld);375 376 return 0;377}378 379static DEFINE_SIMPLE_DEV_PM_OPS(kempld_i2c_pm_ops,380 kempld_i2c_suspend, kempld_i2c_resume);381 382static struct platform_driver kempld_i2c_driver = {383 .driver = {384 .name = "kempld-i2c",385 .pm = pm_sleep_ptr(&kempld_i2c_pm_ops),386 },387 .probe = kempld_i2c_probe,388 .remove_new = kempld_i2c_remove,389};390 391module_platform_driver(kempld_i2c_driver);392 393MODULE_DESCRIPTION("KEM PLD I2C Driver");394MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");395MODULE_LICENSE("GPL");396MODULE_ALIAS("platform:kempld_i2c");397