--- /dev/null
+/*
+ * CBUS I2C driver for Nokia Internet Tablets.
+ *
+ * Copyright (C) 2004-2010 Nokia Corporation
+ *
+ * Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and
+ * Felipe Balbi. Converted to I2C driver by Aaro Koskinen.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * 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/io.h>
+#include <linux/i2c.h>
+#include <linux/gpio.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/i2c-cbus-gpio.h>
+
+/*
+ * Bit counts are derived from Nokia implementation. These should be checked
+ * if other CBUS implementations appear.
+ */
+#define CBUS_ADDR_BITS 3
+#define CBUS_REG_BITS 5
+
+struct cbus_host {
+ spinlock_t lock; /* host lock */
+ struct device *dev;
+ int clk_gpio;
+ int dat_gpio;
+ int sel_gpio;
+};
+
+/**
+ * cbus_send_bit - sends one bit over the bus
+ * @host: the host we're using
+ * @bit: one bit of information to send
+ */
+static void cbus_send_bit(struct cbus_host *host, unsigned bit)
+{
+ gpio_set_value(host->dat_gpio, bit ? 1 : 0);
+ gpio_set_value(host->clk_gpio, 1);
+ gpio_set_value(host->clk_gpio, 0);
+}
+
+/**
+ * cbus_send_data - sends @len amount of data over the bus
+ * @host: the host we're using
+ * @data: the data to send
+ * @len: size of the transfer
+ */
+static void cbus_send_data(struct cbus_host *host, unsigned data, unsigned len)
+{
+ int i;
+
+ for (i = len; i > 0; i--)
+ cbus_send_bit(host, data & (1 << (i - 1)));
+}
+
+/**
+ * cbus_receive_bit - receives one bit from the bus
+ * @host: the host we're using
+ */
+static int cbus_receive_bit(struct cbus_host *host)
+{
+ int ret;
+
+ gpio_set_value(host->clk_gpio, 1);
+ ret = gpio_get_value(host->dat_gpio);
+ gpio_set_value(host->clk_gpio, 0);
+ return ret;
+}
+
+/**
+ * cbus_receive_word - receives 16-bit word from the bus
+ * @host: the host we're using
+ */
+static int cbus_receive_word(struct cbus_host *host)
+{
+ int ret = 0;
+ int i;
+
+ for (i = 16; i > 0; i--) {
+ int bit = cbus_receive_bit(host);
+
+ if (bit < 0)
+ return bit;
+
+ if (bit)
+ ret |= 1 << (i - 1);
+ }
+ return ret;
+}
+
+/**
+ * cbus_transfer - transfers data over the bus
+ * @host: the host we're using
+ * @rw: read/write flag
+ * @dev: device address
+ * @reg: register address
+ * @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0
+ */
+static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev,
+ unsigned reg, unsigned data)
+{
+ unsigned long flags;
+ int ret;
+
+ /* We don't want interrupts disturbing our transfer */
+ spin_lock_irqsave(&host->lock, flags);
+
+ /* Reset state and start of transfer, SEL stays down during transfer */
+ gpio_set_value(host->sel_gpio, 0);
+
+ /* Set the DAT pin to output */
+ gpio_direction_output(host->dat_gpio, 1);
+
+ /* Send the device address */
+ cbus_send_data(host, dev, CBUS_ADDR_BITS);
+
+ /* Send the rw flag */
+ cbus_send_bit(host, rw == I2C_SMBUS_READ);
+
+ /* Send the register address */
+ cbus_send_data(host, reg, CBUS_REG_BITS);
+
+ if (rw == I2C_SMBUS_WRITE) {
+ cbus_send_data(host, data, 16);
+ ret = 0;
+ } else {
+ ret = gpio_direction_input(host->dat_gpio);
+ if (ret) {
+ dev_dbg(host->dev, "failed setting direction\n");
+ goto out;
+ }
+ gpio_set_value(host->clk_gpio, 1);
+
+ ret = cbus_receive_word(host);
+ if (ret < 0) {
+ dev_dbg(host->dev, "failed receiving data\n");
+ goto out;
+ }
+ }
+
+ /* Indicate end of transfer, SEL goes up until next transfer */
+ gpio_set_value(host->sel_gpio, 1);
+ gpio_set_value(host->clk_gpio, 1);
+ gpio_set_value(host->clk_gpio, 0);
+
+out:
+ spin_unlock_irqrestore(&host->lock, flags);
+
+ return ret;
+}
+
+static int cbus_i2c_smbus_xfer(struct i2c_adapter *adapter,
+ u16 addr,
+ unsigned short flags,
+ char read_write,
+ u8 command,
+ int size,
+ union i2c_smbus_data *data)
+{
+ struct cbus_host *chost = i2c_get_adapdata(adapter);
+ int ret;
+
+ if (size != I2C_SMBUS_WORD_DATA)
+ return -EINVAL;
+
+ ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr,
+ command, data->word);
+ if (ret < 0)
+ return ret;
+
+ if (read_write == I2C_SMBUS_READ)
+ data->word = ret;
+
+ return 0;
+}
+
+static u32 cbus_i2c_func(struct i2c_adapter *adapter)
+{
+ return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
+}
+
+static const struct i2c_algorithm cbus_i2c_algo = {
+ .smbus_xfer = cbus_i2c_smbus_xfer,
+ .functionality = cbus_i2c_func,
+};
+
+static int cbus_i2c_remove(struct platform_device *pdev)
+{
+ struct i2c_adapter *adapter = platform_get_drvdata(pdev);
+
+ i2c_del_adapter(adapter);
+
+ return 0;
+}
+
+static int cbus_i2c_probe(struct platform_device *pdev)
+{
+ struct i2c_adapter *adapter;
+ struct cbus_host *chost;
+ int ret;
+
+ adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter),
+ GFP_KERNEL);
+ if (!adapter)
+ return -ENOMEM;
+
+ chost = devm_kzalloc(&pdev->dev, sizeof(*chost), GFP_KERNEL);
+ if (!chost)
+ return -ENOMEM;
+
+ if (pdev->dev.of_node) {
+ struct device_node *dnode = pdev->dev.of_node;
+ if (of_gpio_count(dnode) != 3)
+ return -ENODEV;
+ chost->clk_gpio = of_get_gpio(dnode, 0);
+ chost->dat_gpio = of_get_gpio(dnode, 1);
+ chost->sel_gpio = of_get_gpio(dnode, 2);
+ } else if (dev_get_platdata(&pdev->dev)) {
+ struct i2c_cbus_platform_data *pdata =
+ dev_get_platdata(&pdev->dev);
+ chost->clk_gpio = pdata->clk_gpio;
+ chost->dat_gpio = pdata->dat_gpio;
+ chost->sel_gpio = pdata->sel_gpio;
+ } else {
+ return -ENODEV;
+ }
+
+ adapter->owner = THIS_MODULE;
+ adapter->class = I2C_CLASS_HWMON;
+ adapter->dev.parent = &pdev->dev;
+ adapter->dev.of_node = pdev->dev.of_node;
+ adapter->nr = pdev->id;
+ adapter->timeout = HZ;
+ adapter->algo = &cbus_i2c_algo;
+ strlcpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));
+
+ spin_lock_init(&chost->lock);
+ chost->dev = &pdev->dev;
+
+ ret = devm_gpio_request_one(&pdev->dev, chost->clk_gpio,
+ GPIOF_OUT_INIT_LOW, "CBUS clk");
+ if (ret)
+ return ret;
+
+ ret = devm_gpio_request_one(&pdev->dev, chost->dat_gpio, GPIOF_IN,
+ "CBUS data");
+ if (ret)
+ return ret;
+
+ ret = devm_gpio_request_one(&pdev->dev, chost->sel_gpio,
+ GPIOF_OUT_INIT_HIGH, "CBUS sel");
+ if (ret)
+ return ret;
+
+ i2c_set_adapdata(adapter, chost);
+ platform_set_drvdata(pdev, adapter);
+
+ return i2c_add_numbered_adapter(adapter);
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id i2c_cbus_dt_ids[] = {
+ { .compatible = "i2c-cbus-gpio", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, i2c_cbus_dt_ids);
+#endif
+
+static struct platform_driver cbus_i2c_driver = {
+ .probe = cbus_i2c_probe,
+ .remove = cbus_i2c_remove,
+ .driver = {
+ .name = "i2c-cbus-gpio",
+ .of_match_table = of_match_ptr(i2c_cbus_dt_ids),
+ },
+};
+module_platform_driver(cbus_i2c_driver);
+
+MODULE_ALIAS("platform:i2c-cbus-gpio");
+MODULE_DESCRIPTION("CBUS I2C driver");
+MODULE_AUTHOR("Juha Yrjölä");
+MODULE_AUTHOR("David Weinehall");
+MODULE_AUTHOR("Mikko Ylinen");
+MODULE_AUTHOR("Felipe Balbi");
+MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff