--- /dev/null
+/*
+ * I2C bus driver for Kontron COM modules
+ *
+ * Copyright (c) 2010-2013 Kontron Europe GmbH
+ * Author: Michael Brunner <michael.brunner@kontron.com>
+ *
+ * The driver is based on the i2c-ocores driver by Peter Korsgaard.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/mfd/kempld.h>
+
+#define KEMPLD_I2C_PRELOW 0x0b
+#define KEMPLD_I2C_PREHIGH 0x0c
+#define KEMPLD_I2C_DATA 0x0e
+
+#define KEMPLD_I2C_CTRL 0x0d
+#define I2C_CTRL_IEN 0x40
+#define I2C_CTRL_EN 0x80
+
+#define KEMPLD_I2C_STAT 0x0f
+#define I2C_STAT_IF 0x01
+#define I2C_STAT_TIP 0x02
+#define I2C_STAT_ARBLOST 0x20
+#define I2C_STAT_BUSY 0x40
+#define I2C_STAT_NACK 0x80
+
+#define KEMPLD_I2C_CMD 0x0f
+#define I2C_CMD_START 0x91
+#define I2C_CMD_STOP 0x41
+#define I2C_CMD_READ 0x21
+#define I2C_CMD_WRITE 0x11
+#define I2C_CMD_READ_ACK 0x21
+#define I2C_CMD_READ_NACK 0x29
+#define I2C_CMD_IACK 0x01
+
+#define KEMPLD_I2C_FREQ_MAX 2700 /* 2.7 mHz */
+#define KEMPLD_I2C_FREQ_STD 100 /* 100 kHz */
+
+enum {
+ STATE_DONE = 0,
+ STATE_INIT,
+ STATE_ADDR,
+ STATE_ADDR10,
+ STATE_START,
+ STATE_WRITE,
+ STATE_READ,
+ STATE_ERROR,
+};
+
+struct kempld_i2c_data {
+ struct device *dev;
+ struct kempld_device_data *pld;
+ struct i2c_adapter adap;
+ struct i2c_msg *msg;
+ int pos;
+ int nmsgs;
+ int state;
+ bool was_active;
+};
+
+static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
+module_param(bus_frequency, uint, 0);
+MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
+ __MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");
+
+static int i2c_bus = -1;
+module_param(i2c_bus, int, 0);
+MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");
+
+static bool i2c_gpio_mux;
+module_param(i2c_gpio_mux, bool, 0);
+MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");
+
+/*
+ * kempld_get_mutex must be called prior to calling this function.
+ */
+static int kempld_i2c_process(struct kempld_i2c_data *i2c)
+{
+ struct kempld_device_data *pld = i2c->pld;
+ u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
+ struct i2c_msg *msg = i2c->msg;
+ u8 addr;
+
+ /* Ready? */
+ if (stat & I2C_STAT_TIP)
+ return -EBUSY;
+
+ if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
+ /* Stop has been sent */
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
+ if (i2c->state == STATE_ERROR)
+ return -EIO;
+ return 0;
+ }
+
+ /* Error? */
+ if (stat & I2C_STAT_ARBLOST) {
+ i2c->state = STATE_ERROR;
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
+ return -EAGAIN;
+ }
+
+ if (i2c->state == STATE_INIT) {
+ if (stat & I2C_STAT_BUSY)
+ return -EBUSY;
+
+ i2c->state = STATE_ADDR;
+ }
+
+ if (i2c->state == STATE_ADDR) {
+ /* 10 bit address? */
+ if (i2c->msg->flags & I2C_M_TEN) {
+ addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);
+ i2c->state = STATE_ADDR10;
+ } else {
+ addr = (i2c->msg->addr << 1);
+ i2c->state = STATE_START;
+ }
+
+ /* Set read bit if necessary */
+ addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;
+
+ kempld_write8(pld, KEMPLD_I2C_DATA, addr);
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);
+
+ return 0;
+ }
+
+ /* Second part of 10 bit addressing */
+ if (i2c->state == STATE_ADDR10) {
+ kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
+
+ i2c->state = STATE_START;
+ return 0;
+ }
+
+ if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
+ i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
+
+ if (stat & I2C_STAT_NACK) {
+ i2c->state = STATE_ERROR;
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
+ return -ENXIO;
+ }
+ } else {
+ msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
+ }
+
+ if (i2c->pos >= msg->len) {
+ i2c->nmsgs--;
+ i2c->msg++;
+ i2c->pos = 0;
+ msg = i2c->msg;
+
+ if (i2c->nmsgs) {
+ if (!(msg->flags & I2C_M_NOSTART)) {
+ i2c->state = STATE_ADDR;
+ return 0;
+ } else {
+ i2c->state = (msg->flags & I2C_M_RD)
+ ? STATE_READ : STATE_WRITE;
+ }
+ } else {
+ i2c->state = STATE_DONE;
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
+ return 0;
+ }
+ }
+
+ if (i2c->state == STATE_READ) {
+ kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
+ I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
+ } else {
+ kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
+ }
+
+ return 0;
+}
+
+static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+ int num)
+{
+ struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
+ struct kempld_device_data *pld = i2c->pld;
+ unsigned long timeout = jiffies + HZ;
+ int ret;
+
+ i2c->msg = msgs;
+ i2c->pos = 0;
+ i2c->nmsgs = num;
+ i2c->state = STATE_INIT;
+
+ /* Handle the transfer */
+ while (time_before(jiffies, timeout)) {
+ kempld_get_mutex(pld);
+ ret = kempld_i2c_process(i2c);
+ kempld_release_mutex(pld);
+
+ if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
+ return (i2c->state == STATE_DONE) ? num : ret;
+
+ if (ret == 0)
+ timeout = jiffies + HZ;
+
+ usleep_range(5, 15);
+ }
+
+ i2c->state = STATE_ERROR;
+
+ return -ETIMEDOUT;
+}
+
+/*
+ * kempld_get_mutex must be called prior to calling this function.
+ */
+static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
+{
+ struct kempld_device_data *pld = i2c->pld;
+ u16 prescale_corr;
+ long prescale;
+ u8 ctrl;
+ u8 stat;
+ u8 cfg;
+
+ /* Make sure the device is disabled */
+ ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
+ ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
+ kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
+
+ if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
+ bus_frequency = KEMPLD_I2C_FREQ_MAX;
+
+ if (pld->info.spec_major == 1)
+ prescale = pld->pld_clock / bus_frequency * 5 - 1000;
+ else
+ prescale = pld->pld_clock / bus_frequency * 4 - 3000;
+
+ if (prescale < 0)
+ prescale = 0;
+
+ /* Round to the best matching value */
+ prescale_corr = prescale / 1000;
+ if (prescale % 1000 >= 500)
+ prescale_corr++;
+
+ kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
+ kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);
+
+ /* Activate I2C bus output on GPIO pins */
+ cfg = kempld_read8(pld, KEMPLD_CFG);
+ if (i2c_gpio_mux)
+ cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
+ else
+ cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
+ kempld_write8(pld, KEMPLD_CFG, cfg);
+
+ /* Enable the device */
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
+ ctrl |= I2C_CTRL_EN;
+ kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
+
+ stat = kempld_read8(pld, KEMPLD_I2C_STAT);
+ if (stat & I2C_STAT_BUSY)
+ kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
+}
+
+static u32 kempld_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm kempld_i2c_algorithm = {
+ .master_xfer = kempld_i2c_xfer,
+ .functionality = kempld_i2c_func,
+};
+
+static struct i2c_adapter kempld_i2c_adapter = {
+ .owner = THIS_MODULE,
+ .name = "i2c-kempld",
+ .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
+ .algo = &kempld_i2c_algorithm,
+};
+
+static int kempld_i2c_probe(struct platform_device *pdev)
+{
+ struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
+ struct kempld_i2c_data *i2c;
+ int ret;
+ u8 ctrl;
+
+ i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
+ if (!i2c)
+ return -ENOMEM;
+
+ i2c->pld = pld;
+ i2c->dev = &pdev->dev;
+ i2c->adap = kempld_i2c_adapter;
+ i2c->adap.dev.parent = i2c->dev;
+ i2c_set_adapdata(&i2c->adap, i2c);
+ platform_set_drvdata(pdev, i2c);
+
+ kempld_get_mutex(pld);
+ ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
+
+ if (ctrl & I2C_CTRL_EN)
+ i2c->was_active = true;
+
+ kempld_i2c_device_init(i2c);
+ kempld_release_mutex(pld);
+
+ /* Add I2C adapter to I2C tree */
+ if (i2c_bus >= -1)
+ i2c->adap.nr = i2c_bus;
+ ret = i2c_add_numbered_adapter(&i2c->adap);
+ if (ret)
+ return ret;
+
+ dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
+ bus_frequency);
+
+ return 0;
+}
+
+static int kempld_i2c_remove(struct platform_device *pdev)
+{
+ struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
+ struct kempld_device_data *pld = i2c->pld;
+ u8 ctrl;
+
+ kempld_get_mutex(pld);
+ /*
+ * Disable I2C logic if it was not activated before the
+ * driver loaded
+ */
+ if (!i2c->was_active) {
+ ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
+ ctrl &= ~I2C_CTRL_EN;
+ kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
+ }
+ kempld_release_mutex(pld);
+
+ i2c_del_adapter(&i2c->adap);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM
+static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
+{
+ struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
+ struct kempld_device_data *pld = i2c->pld;
+ u8 ctrl;
+
+ kempld_get_mutex(pld);
+ ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
+ ctrl &= ~I2C_CTRL_EN;
+ kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
+ kempld_release_mutex(pld);
+
+ return 0;
+}
+
+static int kempld_i2c_resume(struct platform_device *pdev)
+{
+ struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
+ struct kempld_device_data *pld = i2c->pld;
+
+ kempld_get_mutex(pld);
+ kempld_i2c_device_init(i2c);
+ kempld_release_mutex(pld);
+
+ return 0;
+}
+#else
+#define kempld_i2c_suspend NULL
+#define kempld_i2c_resume NULL
+#endif
+
+static struct platform_driver kempld_i2c_driver = {
+ .driver = {
+ .name = "kempld-i2c",
+ .owner = THIS_MODULE,
+ },
+ .probe = kempld_i2c_probe,
+ .remove = kempld_i2c_remove,
+ .suspend = kempld_i2c_suspend,
+ .resume = kempld_i2c_resume,
+};
+
+module_platform_driver(kempld_i2c_driver);
+
+MODULE_DESCRIPTION("KEM PLD I2C Driver");
+MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:kempld_i2c");
projects / linux-beck.git / commitdiff