From: Aaro Koskinen <aaro.koskinen@iki.fi>
To: linux-omap@vger.kernel.org
Cc: linux-i2c@vger.kernel.org
Subject: [RFC PATCH 1/5] i2c: introduce i2c-cbus driver
Date: Wed, 29 Aug 2012 00:34:23 +0300 [thread overview]
Message-ID: <1346189667-32330-2-git-send-email-aaro.koskinen@iki.fi> (raw)
In-Reply-To: <1346189667-32330-1-git-send-email-aaro.koskinen@iki.fi>
Add i2c driver to enable access to devices behind CBUS on Nokia Internet
Tablets.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-i2c@vger.kernel.org
---
drivers/i2c/busses/Kconfig | 10 ++
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-cbus.c | 342 +++++++++++++++++++++++++++++++++++++++++
include/linux/i2c-cbus.h | 27 ++++
4 files changed, 380 insertions(+), 0 deletions(-)
create mode 100644 drivers/i2c/busses/i2c-cbus.c
create mode 100644 include/linux/i2c-cbus.h
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index b4aaa1b..184ef43 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -331,6 +331,16 @@ config I2C_BLACKFIN_TWI_CLK_KHZ
help
The unit of the TWI clock is kHz.
+config I2C_CBUS
+ tristate "CBUS I2C driver"
+ depends on GENERIC_GPIO
+ help
+ Support for CBUS access using I2C API. Mostly relevant for Nokia
+ Internet Tablets (770, N800 and N810).
+
+ This driver can also be built as a module. If so, the module
+ will be called i2c-cbus.
+
config I2C_CPM
tristate "Freescale CPM1 or CPM2 (MPC8xx/826x)"
depends on (CPM1 || CPM2) && OF_I2C
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index ce3c2be..44dbfd1 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o
obj-$(CONFIG_I2C_AT91) += i2c-at91.o
obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o
obj-$(CONFIG_I2C_BLACKFIN_TWI) += i2c-bfin-twi.o
+obj-$(CONFIG_I2C_CBUS) += i2c-cbus.o
obj-$(CONFIG_I2C_CPM) += i2c-cpm.o
obj-$(CONFIG_I2C_DAVINCI) += i2c-davinci.o
obj-$(CONFIG_I2C_DESIGNWARE_PLATFORM) += i2c-designware-platform.o
diff --git a/drivers/i2c/busses/i2c-cbus.c b/drivers/i2c/busses/i2c-cbus.c
new file mode 100644
index 0000000..3cc5be4
--- /dev/null
+++ b/drivers/i2c/busses/i2c-cbus.c
@@ -0,0 +1,342 @@
+/*
+ * 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/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-cbus.h>
+#include <linux/io.h>
+
+struct cbus_host {
+ /* host lock */
+ spinlock_t 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
+ * @input: whether to set data pin as input after sending
+ */
+static int cbus_send_bit(struct cbus_host *host, unsigned bit,
+ unsigned input)
+{
+ int ret = 0;
+
+ gpio_set_value(host->dat_gpio, bit ? 1 : 0);
+ gpio_set_value(host->clk_gpio, 1);
+
+ /* The data bit is read on the rising edge of CLK */
+ if (input)
+ ret = gpio_direction_input(host->dat_gpio);
+
+ gpio_set_value(host->clk_gpio, 0);
+
+ return ret;
+}
+
+/**
+ * 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
+ * @input: whether to set data pin as input after sending
+ */
+static int cbus_send_data(struct cbus_host *host, unsigned data, unsigned len,
+ unsigned input)
+{
+ int ret = 0;
+ int i;
+
+ for (i = len; i > 0; i--) {
+ ret = cbus_send_bit(host, data & (1 << (i - 1)),
+ input && (i == 1));
+ if (ret < 0)
+ goto out;
+ }
+
+out:
+ return ret;
+}
+
+/**
+ * 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);
+ if (ret < 0)
+ goto out;
+ gpio_set_value(host->clk_gpio, 0);
+
+out:
+ 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)
+ goto out;
+
+ if (bit)
+ ret |= 1 << (i - 1);
+ }
+
+out:
+ 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 */
+ ret = cbus_send_data(host, dev, 3, 0);
+ if (ret < 0) {
+ dev_dbg(host->dev, "failed sending device addr\n");
+ goto out;
+ }
+
+ /* Send the rw flag */
+ ret = cbus_send_bit(host, rw == I2C_SMBUS_READ, 0);
+ if (ret < 0) {
+ dev_dbg(host->dev, "failed sending read/write flag\n");
+ goto out;
+ }
+
+ /* Send the device address */
+ ret = cbus_send_data(host, reg, 5, rw == I2C_SMBUS_READ);
+ if (ret < 0) {
+ dev_dbg(host->dev, "failed sending register addr\n");
+ goto out;
+ }
+
+ if (rw == I2C_SMBUS_WRITE) {
+ ret = cbus_send_data(host, data, 16, 0);
+ if (ret < 0) {
+ dev_dbg(host->dev, "failed sending data\n");
+ goto out;
+ }
+ } else {
+ 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);
+ struct cbus_host *chost = i2c_get_adapdata(adapter);
+ int ret;
+
+ ret = i2c_del_adapter(adapter);
+ if (ret)
+ return ret;
+ gpio_free(chost->clk_gpio);
+ gpio_free(chost->dat_gpio);
+ gpio_free(chost->sel_gpio);
+ kfree(chost);
+ kfree(adapter);
+ platform_set_drvdata(pdev, NULL);
+
+ return 0;
+}
+
+static int cbus_i2c_probe(struct platform_device *pdev)
+{
+ struct i2c_cbus_platform_data *pdata = pdev->dev.platform_data;
+ struct i2c_adapter *adapter;
+ struct cbus_host *chost;
+ struct gpio gpios[3];
+ int ret;
+
+ adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
+ if (!adapter) {
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ chost = kzalloc(sizeof(*chost), GFP_KERNEL);
+ if (!chost) {
+ ret = -ENOMEM;
+ goto error_mem;
+ }
+
+ adapter->owner = THIS_MODULE;
+ adapter->class = I2C_CLASS_HWMON;
+ adapter->dev.parent = &pdev->dev;
+ 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;
+
+ gpios[0].gpio = chost->clk_gpio = pdata->clk_gpio;
+ gpios[0].flags = GPIOF_OUT_INIT_LOW;
+ gpios[0].label = "CBUS clk";
+
+ gpios[1].gpio = chost->dat_gpio = pdata->dat_gpio;
+ gpios[1].flags = GPIOF_IN;
+ gpios[1].label = "CBUS data";
+
+ gpios[2].gpio = chost->sel_gpio = pdata->sel_gpio;
+ gpios[2].flags = GPIOF_OUT_INIT_HIGH;
+ gpios[2].label = "CBUS sel";
+
+ ret = gpio_request_array(gpios, ARRAY_SIZE(gpios));
+ if (ret)
+ goto error_gpio;
+
+ gpio_set_value(chost->clk_gpio, 1);
+ gpio_set_value(chost->clk_gpio, 0);
+
+ i2c_set_adapdata(adapter, chost);
+ platform_set_drvdata(pdev, adapter);
+
+ ret = i2c_add_numbered_adapter(adapter);
+ if (ret)
+ goto error_i2c;
+
+ return 0;
+
+error_i2c:
+ gpio_free_array(gpios, ARRAY_SIZE(gpios));
+error_gpio:
+ kfree(chost);
+error_mem:
+ kfree(adapter);
+error:
+ return ret;
+}
+
+static struct platform_driver cbus_i2c_driver = {
+ .probe = cbus_i2c_probe,
+ .remove = cbus_i2c_remove,
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = "i2c-cbus",
+ },
+};
+module_platform_driver(cbus_i2c_driver);
+
+MODULE_ALIAS("platform:i2c-cbus");
+MODULE_DESCRIPTION("CBUS I2C driver");
+MODULE_AUTHOR("Juha Yrjölä");
+MODULE_AUTHOR("David Weinehall");
+MODULE_AUTHOR("Mikko Ylinen");
+MODULE_AUTHOR("Felipe Balbi <felipe.balbi@nokia.com>");
+MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/i2c-cbus.h b/include/linux/i2c-cbus.h
new file mode 100644
index 0000000..636d726
--- /dev/null
+++ b/include/linux/i2c-cbus.h
@@ -0,0 +1,27 @@
+/*
+ * i2c-cbus.h - CBUS I2C platform_data definition
+ *
+ * Copyright (C) 2004-2009 Nokia Corporation
+ *
+ * Written by Felipe Balbi and 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.
+ */
+
+#ifndef __INCLUDE_LINUX_I2C_CBUS_H
+#define __INCLUDE_LINUX_I2C_CBUS_H
+
+struct i2c_cbus_platform_data {
+ int dat_gpio;
+ int clk_gpio;
+ int sel_gpio;
+};
+
+#endif /* __INCLUDE_LINUX_I2C_CBUS_H */
--
1.7.2.5
--
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next parent reply other threads:[~2012-08-28 21:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1346189667-32330-1-git-send-email-aaro.koskinen@iki.fi>
2012-08-28 21:34 ` Aaro Koskinen [this message]
2012-08-29 23:35 ` [RFC PATCH 1/5] i2c: introduce i2c-cbus driver Tony Lindgren
[not found] ` <1346189667-32330-2-git-send-email-aaro.koskinen-X3B1VOXEql0@public.gmane.org>
2012-08-30 15:34 ` Felipe Balbi
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