Message-ID: <20121031183449.GC28100@arwen.pp.htv.fi>
Date:	Wed, 31 Oct 2012 20:34:49 +0200
From:	Felipe Balbi <balbi@...com>
To:	Aaro Koskinen <aaro.koskinen@....fi>
CC:	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-i2c@...r.kernel.org>
Subject: Re: [PATCH v2 1/4] i2c: introduce i2c-cbus driver

On Wed, Oct 31, 2012 at 08:03:43PM +0200, Aaro Koskinen wrote:
> Add i2c driver to enable access to devices behind CBUS on Nokia Internet
> Tablets.
> 
> The patch also adds CBUS I2C configuration for N8x0 which is one of the
> users of this driver.
> 
> Cc: linux-i2c@...r.kernel.org
> Acked-by: Felipe Balbi <balbi@...com>
> Acked-by: Tony Lindgren <tony@...mide.com>
> Signed-off-by: Aaro Koskinen <aaro.koskinen@....fi>
> ---
>  arch/arm/mach-omap2/board-n8x0.c |   42 ++++++
>  drivers/i2c/busses/Kconfig       |   10 ++
>  drivers/i2c/busses/Makefile      |    1 +
>  drivers/i2c/busses/i2c-cbus.c    |  300 ++++++++++++++++++++++++++++++++++++++
>  include/linux/i2c-cbus.h         |   27 ++++
>  5 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/arch/arm/mach-omap2/board-n8x0.c b/arch/arm/mach-omap2/board-n8x0.c
> index d95f727..7ea0348 100644
> --- a/arch/arm/mach-omap2/board-n8x0.c
> +++ b/arch/arm/mach-omap2/board-n8x0.c
> @@ -16,8 +16,10 @@
>  #include <linux/gpio.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
> +#include <linux/irq.h>
>  #include <linux/stddef.h>
>  #include <linux/i2c.h>
> +#include <linux/i2c-cbus.h>
>  #include <linux/spi/spi.h>
>  #include <linux/usb/musb.h>
>  #include <linux/platform_data/spi-omap2-mcspi.h>
> @@ -39,6 +41,45 @@
>  #define TUSB6010_GPIO_ENABLE	0
>  #define TUSB6010_DMACHAN	0x3f
>  
> +#if defined(CONFIG_I2C_CBUS) || defined(CONFIG_I2C_CBUS_MODULE)
> +static struct i2c_cbus_platform_data n8x0_cbus_data = {
> +	.clk_gpio = 66,
> +	.dat_gpio = 65,
> +	.sel_gpio = 64,
> +};
> +
> +static struct platform_device n8x0_cbus_device = {
> +	.name	= "i2c-cbus",
> +	.id	= 3,
> +	.dev	= {
> +		.platform_data = &n8x0_cbus_data,
> +	},
> +};
> +
> +static struct i2c_board_info n8x0_i2c_board_info_3[] __initdata = {
> +	{
> +		I2C_BOARD_INFO("retu-mfd", 0x01),
> +	},
> +};
> +
> +static void __init n8x0_cbus_init(void)
> +{
> +	const int retu_irq_gpio = 108;
> +
> +	if (gpio_request_one(retu_irq_gpio, GPIOF_IN, "Retu IRQ"))
> +		return;
> +	irq_set_irq_type(gpio_to_irq(retu_irq_gpio), IRQ_TYPE_EDGE_RISING);
> +	n8x0_i2c_board_info_3[0].irq = gpio_to_irq(retu_irq_gpio);
> +	i2c_register_board_info(3, n8x0_i2c_board_info_3,
> +				ARRAY_SIZE(n8x0_i2c_board_info_3));
> +	platform_device_register(&n8x0_cbus_device);
> +}
> +#else /* CONFIG_I2C_CBUS */
> +static void __init n8x0_cbus_init(void)
> +{
> +}
> +#endif /* CONFIG_I2C_CBUS */
> +
>  #if defined(CONFIG_USB_MUSB_TUSB6010) || defined(CONFIG_USB_MUSB_TUSB6010_MODULE)
>  /*
>   * Enable or disable power to TUSB6010. When enabling, turn on 3.3 V and
> @@ -677,6 +718,7 @@ static void __init n8x0_init_machine(void)
>  	gpmc_onenand_init(board_onenand_data);
>  	n8x0_mmc_init();
>  	n8x0_usb_init();
> +	n8x0_cbus_init();
>  }
>  
>  MACHINE_START(NOKIA_N800, "Nokia N800")
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 65dd599..d01c8ef 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -338,6 +338,16 @@ 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 2d33d62..3c548b1 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_CORE)	+= i2c-designware-core.o
> diff --git a/drivers/i2c/busses/i2c-cbus.c b/drivers/i2c/busses/i2c-cbus.c
> new file mode 100644
> index 0000000..1ea7667
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-cbus.c
> @@ -0,0 +1,300 @@
> +/*
> + * 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/init.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/i2c-cbus.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;
> +	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);
> +
> +	return i2c_del_adapter(adapter);
> +}
> +
> +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 (pdev->dev.platform_data) {
> +		struct i2c_cbus_platform_data *pdata = pdev->dev.platform_data;
> +		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->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", },
> +	{ }
> +};
> +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	= {
> +		.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");
> +MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@....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

looks like this should be under include/linux/platform_data/ ? No strong
feelings though.

> @@ -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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-- 
balbi

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