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-rw-r--r--drivers/i2c/busses/i2c-cbus-gpio.c284
1 files changed, 284 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-cbus-gpio.c b/drivers/i2c/busses/i2c-cbus-gpio.c
new file mode 100644
index 000000000..d97c61eec
--- /dev/null
+++ b/drivers/i2c/busses/i2c-cbus-gpio.c
@@ -0,0 +1,284 @@
+/*
+ * 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/slab.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.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;
+ struct gpio_desc *clk;
+ struct gpio_desc *dat;
+ struct gpio_desc *sel;
+};
+
+/**
+ * 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)
+{
+ gpiod_set_value(host->dat, bit ? 1 : 0);
+ gpiod_set_value(host->clk, 1);
+ gpiod_set_value(host->clk, 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;
+
+ gpiod_set_value(host->clk, 1);
+ ret = gpiod_get_value(host->dat);
+ gpiod_set_value(host->clk, 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 */
+ gpiod_set_value(host->sel, 0);
+
+ /* Set the DAT pin to output */
+ gpiod_direction_output(host->dat, 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 = gpiod_direction_input(host->dat);
+ if (ret) {
+ dev_dbg(host->dev, "failed setting direction\n");
+ goto out;
+ }
+ gpiod_set_value(host->clk, 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 */
+ gpiod_set_value(host->sel, 1);
+ gpiod_set_value(host->clk, 1);
+ gpiod_set_value(host->clk, 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,
+ .smbus_xfer_atomic = 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;
+
+ 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 (gpiod_count(&pdev->dev, NULL) != 3)
+ return -ENODEV;
+ chost->clk = devm_gpiod_get_index(&pdev->dev, NULL, 0, GPIOD_OUT_LOW);
+ if (IS_ERR(chost->clk))
+ return PTR_ERR(chost->clk);
+ chost->dat = devm_gpiod_get_index(&pdev->dev, NULL, 1, GPIOD_IN);
+ if (IS_ERR(chost->dat))
+ return PTR_ERR(chost->dat);
+ chost->sel = devm_gpiod_get_index(&pdev->dev, NULL, 2, GPIOD_OUT_HIGH);
+ if (IS_ERR(chost->sel))
+ return PTR_ERR(chost->sel);
+ gpiod_set_consumer_name(chost->clk, "CBUS clk");
+ gpiod_set_consumer_name(chost->dat, "CBUS dat");
+ gpiod_set_consumer_name(chost->sel, "CBUS sel");
+
+ 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;
+ strscpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));
+
+ spin_lock_init(&chost->lock);
+ chost->dev = &pdev->dev;
+
+ 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");