Re: [PATCH v2 2/2] i2c: Add support for Ux500/Nomadik I2C controller

[Ben Dooks <ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>]

On Fri, Jan 08, 2010 at 04:02:55PM +0530, srinidhi kasagar wrote:
> This adds support for the ST-Ericsson's I2C
> block found in Ux500 and Nomadik 8815
> platforms.

Please re-wrap, it could lose at-least one line.
 
> Signed-off-by: srinidhi kasagar <srinidhi.kasagar-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
> Acked-by: Andrea gallo <andrea.gallo-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
> Acked-by: Linus Walleij <linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
> ---
>  drivers/i2c/busses/Kconfig       |    7 +
>  drivers/i2c/busses/Makefile      |    1 +
>  drivers/i2c/busses/i2c-nomadik.c |  980 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 988 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/i2c/busses/i2c-nomadik.c
> 
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 5f318ce..fbde486 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -439,6 +439,13 @@ config I2C_MV64XXX
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called i2c-mv64xxx.
>  
> +config I2C_NOMADIK
> +	tristate "ST-Ericsson Nomadik/Ux500 I2C Controller"
> +	depends on PLAT_NOMADIK
> +	help
> +	  If you say yes to this option, support will be included for the
> +	  I2C interface from ST-Ericsson's Nomadik and Ux500 architectures.
> +
>  config I2C_OCORES
>  	tristate "OpenCores I2C Controller"
>  	depends on EXPERIMENTAL
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 302c551..10dd8b5 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -42,6 +42,7 @@ obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
>  obj-$(CONFIG_I2C_IXP2000)	+= i2c-ixp2000.o
>  obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
>  obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o
> +obj-$(CONFIG_I2C_NOMADIK)	+= i2c-nomadik.o
>  obj-$(CONFIG_I2C_OCORES)	+= i2c-ocores.o
>  obj-$(CONFIG_I2C_OMAP)		+= i2c-omap.o
>  obj-$(CONFIG_I2C_PASEMI)	+= i2c-pasemi.o
> diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
> new file mode 100644
> index 0000000..b228dca
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-nomadik.c
> @@ -0,0 +1,980 @@
> +/*
> + * Copyright (C) 2009 ST-Ericsson
> + * Copyright (C) 2009 STMicroelectronics
> + *
> + * I2C master mode controller driver, used in Nomadik 8815
> + * and Ux500 platforms.
> + *
> + * Author: Srinidhi Kasagar <srinidhi.kasagar-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
> + * Author: Sachin Verma <sachin.verma-qxv4g6HH51o@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2, as
> + * published by the Free Software Foundation.
> + */
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/i2c.h>
> +#include <linux/err.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +
> +#include <plat/i2c.h>
> +
> +#define DRIVER_NAME "nmk-i2c"
> +
> +/* I2C Controller register offsets */
> +#define I2C_CR		(0x000)
> +#define I2C_SCR		(0x004)
> +#define I2C_HSMCR	(0x008)
> +#define I2C_MCR		(0x00C)
> +#define I2C_TFR		(0x010)
> +#define I2C_SR		(0x014)
> +#define I2C_RFR		(0x018)
> +#define I2C_TFTR	(0x01C)
> +#define I2C_RFTR	(0x020)
> +#define I2C_DMAR	(0x024)
> +#define I2C_BRCR	(0x028)
> +#define I2C_IMSCR	(0x02C)
> +#define I2C_RISR	(0x030)
> +#define I2C_MISR	(0x034)
> +#define I2C_ICR		(0x038)
> +
> +/* Control register bit positions */
> +#define I2C_CR_PE_POS		0	/* Peripheral Enable */
> +#define I2C_CR_OM_POS		1	/* Operating mode */
> +#define I2C_CR_SAM_POS		3	/* Slave addressing mode */
> +#define I2C_CR_SM_POS		4	/* Speed mode */
> +#define I2C_CR_SGCM_POS		6	/* Slave general call mode */
> +#define I2C_CR_FTX_POS		7	/* Flush Transmit */
> +#define I2C_CR_FRX_POS		8	/* Flush Receive */
> +#define I2C_CR_DMA_TX_EN_POS 	9	/* DMA Tx enable */
> +#define I2C_CR_DMA_RX_EN_POS	10	/* DMA Rx Enable */
> +#define I2C_CR_DMA_SLE_POS	11	/* DMA sync. logic enable */
> +#define I2C_CR_LM_POS		12	/* Loopback mode */
> +#define I2C_CR_FON_POS		13	/* Filtering on */
> +#define I2C_CR_FS_POS		15	/* Force stop enable */
> +
> +#define I2C_CR_PE		(0x1 << I2C_CR_PE_POS)
> +#define I2C_CR_OM		(0x3 << I2C_CR_OM_POS)
> +#define I2C_CR_SAM		(0x1 << I2C_CR_SAM_POS)
> +#define I2C_CR_SM		(0x3 << I2C_CR_SM_POS)
> +#define I2C_CR_SGCM		(0x1 << I2C_CR_SGCM_POS)
> +#define I2C_CR_FTX		(0x1 << I2C_CR_FTX_POS)
> +#define I2C_CR_FRX		(0x1 << I2C_CR_FRX_POS)
> +#define I2C_CR_DMA_TX_EN	(0x1 << I2C_CR_DMA_TX_EN_POS)
> +#define I2C_CR_DMA_RX_EN	(0x1 << I2C_CR_DMA_RX_EN_POS)
> +#define I2C_CR_DMA_SLE		(0x1 << I2C_CR_DMA_SLE_POS)
> +#define I2C_CR_LM		(0x1 << I2C_CR_LM_POS)
> +#define I2C_CR_FON		(0x3 << I2C_CR_FON_POS)
> +#define I2C_CR_FS		(0x3 << I2C_CR_FS_POS)

do we really need the POS and the actaul register definitios, why
not squash these down a bit?

> +/* Master controller (MCR) bit positions */
> +#define I2C_MCR_OP_POS  	0	/* Operation */
> +#define I2C_MCR_A7_POS		1	/* 7-bit address */
> +#define I2C_MCR_EA10_POS	8	/* 10-bit Extended address */
> +#define I2C_MCR_SB_POS		11	/* Extended address */
> +#define I2C_MCR_AM_POS		12	/* Address type */
> +#define I2C_MCR_STOP_POS 	14	/* Stop condition */
> +#define I2C_MCR_LENGTH_POS	15	/* Transaction length */
> +
> +#define I2C_MCR_OP		(0x1 << I2C_MCR_OP_POS)
> +#define I2C_MCR_A7		(0x7F << I2C_MCR_A7_POS)
> +#define I2C_MCR_EA10		(0x7 << I2C_MCR_EA10_POS)
> +#define I2C_MCR_SB		(0x1 << I2C_MCR_SB_POS)
> +#define I2C_MCR_AM		(0x3 << I2C_MCR_AM_POS)
> +#define I2C_MCR_STOP		(0x1 << I2C_MCR_STOP_POS)
> +#define I2C_MCR_LENGTH		(0x7FF << I2C_MCR_LENGTH_POS)
> +
> +/* Status register (SR) */
> +#define I2C_SR_OP		(0x3 << 0)	/* Operation */
> +#define I2C_SR_STATUS		(0x3 << 2)	/* controller status */
> +#define I2C_SR_CAUSE		(0x7 << 4)	/* Abort cause */
> +#define I2C_SR_TYPE		(0x3 << 7)	/* Receive type */
> +#define I2C_SR_LENGTH		(0x7FF << 9)	/* Transfer length */
> +
> +/* Interrupt mask set/clear (IMSCR) bits */
> +#define I2C_IT_TXFE 		(0x1 << 0)
> +#define I2C_IT_TXFNE		(0x1 << 1)
> +#define I2C_IT_TXFF		(0x1 << 2)
> +#define I2C_IT_TXFOVR		(0x1 << 3)
> +#define I2C_IT_RXFE		(0x1 << 4)
> +#define I2C_IT_RXFNF		(0x1 << 5)
> +#define I2C_IT_RXFF		(0x1 << 6)
> +#define I2C_IT_RFSR		(0x1 << 16)
> +#define I2C_IT_RFSE		(0x1 << 17)
> +#define I2C_IT_WTSR		(0x1 << 18)
> +#define I2C_IT_MTD		(0x1 << 19)
> +#define I2C_IT_STD		(0x1 << 20)
> +#define I2C_IT_MAL		(0x1 << 24)
> +#define I2C_IT_BERR		(0x1 << 25)
> +#define I2C_IT_MTDWS		(0x1 << 28)
> +
> +#define GEN_MASK(val, mask, sb)  (((val) << (sb)) & (mask))
> +
> +/* some bits in ICR are reserved */
> +#define I2C_CLEAR_ALL_INTS	0x131F007F
> +
> +/* first three msb bits are reserved */
> +#define IRQ_MASK(mask)		(mask & 0x1fffffff)
> +
> +/* maximum threshold value */
> +#define MAX_I2C_FIFO_THRESHOLD	15
> +
> +#define i2c_set_bit(reg, mask)	(writel(readl(reg) | mask, (reg)))
> +#define i2c_clr_bit(reg, mask)	(writel(readl(reg) & ~(mask), (reg)))

would prefer to see these as inline functions.

> +enum {
> +	I2C_NOP,
> +	I2C_ON_GOING,
> +	I2C_OK,
> +	I2C_ABORT
> +};

anonymous?

> +/* operation */
> +enum i2c_operation {
> +	I2C_NO_OPERATION = 0xff,
> +	I2C_WRITE = 0x00,
> +	I2C_READ = 0x01
> +};
> +
> +/* controller response timeout in ms */
> +#define I2C_TIMEOUT_MS	500
> +
> +/**
> + * struct i2c_nmk_client - client specific data
> + * @slave_adr: 7-bit slave address
> + * @count: no. bytes to be transfered
> + * @buffer: client data buffer
> + * @xfer_bytes: bytes transfered till now
> + * @operation: current I2C operation
> + */
> +struct i2c_nmk_client {
> +	unsigned short		slave_adr;
> +	unsigned long		count;
> +	unsigned char		*buffer;
> +	unsigned long		xfer_bytes;
> +	enum i2c_operation	operation;
> +};
> +
> +/**
> + * struct nmk_i2c_dev - private data structure of the controller
> + * @pdev: parent platform device
> + * @adap: corresponding I2C adapter
> + * @irq: interrupt line for the controller
> + * @virtbase: virtual io memory area
> + * @clk: hardware i2c block clock
> + * @cfg: machine provided controller configuration
> + * @cli: holder of client specific data
> + * @stop: stop condition
> + * @xfer_complete: acknowledge completion for a I2C message
> + * @result: controller propogated result
> + */
> +struct nmk_i2c_dev {
> +	struct platform_device		*pdev;
> +	struct i2c_adapter 		adap;
> +	int 				irq;
> +	void __iomem			*virtbase;
> +	struct clk			*clk;
> +	struct nmk_i2c_controller	cfg;
> +	struct i2c_nmk_client		cli;
> +	int 				stop;
> +	struct completion		xfer_complete;
> +	int 				result;
> +};
> +
> +/* controller's abort causes */
> +static const char *abort_causes[] = {
> +	"no ack received after address transmission",
> +	"no ack received during data phase",
> +	"ack received after xmission of master code",
> +	"master lost arbitration",
> +	"slave restarts",
> +	"slave reset",
> +	"overflow, maxsize is 2047 bytes",
> +};
> +
> +static unsigned int nmk_i2c_functionality(struct i2c_adapter *adap);
> +static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
> +		struct i2c_msg msgs[], int num_msgs);
> +
> +static const struct i2c_algorithm nmk_i2c_algo = {
> +	.master_xfer	= nmk_i2c_xfer,
> +	.functionality	= nmk_i2c_functionality
> +};
> +
> +static unsigned int nmk_i2c_functionality(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C
> +		| I2C_FUNC_SMBUS_BYTE_DATA
> +		| I2C_FUNC_SMBUS_WORD_DATA
> +		| I2C_FUNC_SMBUS_I2C_BLOCK;
> +}

putting these later in the driver would avoid having to
forward declare them, and move them close to their registration
points. would be nice to get this fixed before merge.

> +/**
> + * flush_i2c_fifo() - This function flushes the I2C FIFO
> + * @dev: private data of I2C Driver
> + *
> + * This function flushes the I2C Tx and Rx FIFOs. It returns
> + * 0 on successful flushing of FIFO
> + */
> +static int flush_i2c_fifo(struct nmk_i2c_dev *dev)
> +{
> +#define LOOP_ATTEMPTS 10
> +	int i;
> +	unsigned long timeout;
> +
> +	/*
> +	 * flush the transmit and receive FIFO. The flushing
> +	 * operation takes several cycles before to be completed.
> +	 * On the completion, the I2C internal logic clears these
> +	 * bits, until then no one must access Tx, Rx FIFO and
> +	 * should poll on these bits waiting for the completion.
> +	 */
> +	writel((I2C_CR_FTX | I2C_CR_FRX), dev->virtbase + I2C_CR);
> +
> +	for (i = 0; i < LOOP_ATTEMPTS; i++) {
> +		timeout = jiffies + msecs_to_jiffies(I2C_TIMEOUT_MS);
> +
> +		while (!time_after(jiffies, timeout)) {
> +			if ((readl(dev->virtbase + I2C_CR) &
> +				(I2C_CR_FTX | I2C_CR_FRX)) == 0)
> +					return 0;
> +		}
> +	}
> +
> +	dev_err(&dev->pdev->dev, "flushing operation timed out "
> +		"giving up after %d attempts", LOOP_ATTEMPTS);
> +
> +	return -ETIMEDOUT;
> +}
> +
> +/**
> + * disable_all_interrupts() - Disable all interrupts of this I2c Bus
> + * @dev: private data of I2C Driver
> + */
> +static void disable_all_interrupts(struct nmk_i2c_dev *dev)
> +{
> +	u32 mask = 0;
> +	mask = IRQ_MASK(mask);

that looks like a job for
	u32 mask = IRQ_MASK(0);

> +	writel(mask, dev->virtbase + I2C_IMSCR);
> +}
> +
> +/**
> + * clear_all_interrupts() - Clear all interrupts of I2C Controller
> + * @dev: private data of I2C Driver
> + */
> +static void clear_all_interrupts(struct nmk_i2c_dev *dev)
> +{
> +	u32 mask;
> +	mask = IRQ_MASK(I2C_CLEAR_ALL_INTS);
> +	writel(mask, dev->virtbase + I2C_ICR);
> +}
> +
> +/**
> + * init_hw() - initialize the I2C hardware
> + * @dev: private data of I2C Driver
> + */
> +static int init_hw(struct nmk_i2c_dev *dev)
> +{
> +	int stat;
> +
> +	stat = flush_i2c_fifo(dev);
> +	if (stat)
> +		return stat;
> +
> +	/* disable the controller */
> +	i2c_clr_bit(dev->virtbase + I2C_CR , I2C_CR_PE);
> +
> +	disable_all_interrupts(dev);
> +
> +	clear_all_interrupts(dev);
> +
> +	dev->cli.operation = I2C_NO_OPERATION;
> +
> +	return 0;
> +}
> +
> +/* enable peripheral, master mode operation */
> +#define DEFAULT_I2C_REG_CR 	((1 << I2C_CR_OM_POS) | I2C_CR_PE)
> +
> +/**
> + * load_i2c_mcr_reg() - load the MCR register
> + * @dev: private data of controller
> + */
> +static u32 load_i2c_mcr_reg(struct nmk_i2c_dev *dev)
> +{
> +	u32 mcr = 0;
> +
> +	/* 7-bit address transaction */
> +	mcr |= GEN_MASK(1, I2C_MCR_AM, I2C_MCR_AM_POS);
> +	mcr |= GEN_MASK(dev->cli.slave_adr, I2C_MCR_A7, I2C_MCR_A7_POS);
> +
> +	/* start byte procedure not applied */
> +	mcr |= GEN_MASK(0, I2C_MCR_SB, I2C_MCR_SB_POS);
> +
> +	/* check the operation, master read/write? */
> +	if (dev->cli.operation == I2C_WRITE)
> +		mcr |= GEN_MASK(I2C_WRITE, I2C_MCR_OP, I2C_MCR_OP_POS);
> +	else
> +		mcr |= GEN_MASK(I2C_READ, I2C_MCR_OP, I2C_MCR_OP_POS);
> +
> +	/* stop or repeated start? */
> +	if (dev->stop)
> +		mcr |= GEN_MASK(1, I2C_MCR_STOP, I2C_MCR_STOP_POS);
> +	else
> +		mcr &= ~(GEN_MASK(1, I2C_MCR_STOP, I2C_MCR_STOP_POS));
> +
> +	mcr |= GEN_MASK(dev->cli.count, I2C_MCR_LENGTH,
> +					I2C_MCR_LENGTH_POS);
> +	return mcr;
> +}
> +
> +/**
> + * setup_i2c_controller() - setup the controller
> + * @dev: private data of controller
> + */
> +static void setup_i2c_controller(struct nmk_i2c_dev *dev)
> +{
> +	u32 brcr1, brcr2;
> +	u32 i2c_clk, div;
> +
> +	writel(0x0, dev->virtbase + I2C_CR);
> +	writel(0x0, dev->virtbase + I2C_HSMCR);
> +	writel(0x0, dev->virtbase + I2C_TFTR);
> +	writel(0x0, dev->virtbase + I2C_RFTR);
> +	writel(0x0, dev->virtbase + I2C_DMAR);
> +
> +	/*
> +	 * set the slsu:
> +	 *
> +	 * slsu defines the data setup time after SCL clock
> +	 * stretching in terms of i2c clk cycles. The
> +	 * needed setup time for the three modes are 250ns,
> +	 * 100ns, 10ns repectively thus leading to the values
> +	 * of 14, 6, 2 for a 48 MHz i2c clk.
> +	 */
> +	writel(dev->cfg.slsu << 16, dev->virtbase + I2C_SCR);
> +
> +	i2c_clk = clk_get_rate(dev->clk);
> +
> +	/* fallback to std. mode if machine has not provided it */
> +	if (dev->cfg.clk_freq == 0)
> +		dev->cfg.clk_freq = 100000;
> +
> +	/*
> +	 * The spec says, in case of std. mode the divider is
> +	 * 2 whereas it is 3 for fast and fastplus mode of
> +	 * operation. TODO - high speed support.
> +	 */
> +	div = (dev->cfg.clk_freq > 100000) ? 3 : 2;
> +
> +	/*
> +	 * generate the mask for baud rate counters. The controller
> +	 * has two baud rate counters. One is used for High speed
> +	 * operation, and the other is for std, fast mode, fast mode
> +	 * plus operation. Currently we do not supprt high speed mode
> +	 * so set brcr1 to 0.
> +	 */
> +	brcr1 = 0 << 16;
> +	brcr2 = (i2c_clk/(dev->cfg.clk_freq * div)) & 0xffff;
> +
> +	/* set the baud rate counter register */
> +	writel((brcr1 | brcr2), dev->virtbase + I2C_BRCR);
> +
> +	/*
> +	 * set the speed mode. Currently we support
> +	 * only standard and fast mode of operation
> +	 * TODO - support for fast mode plus (upto 1Mb/s)
> +	 * and high speed (up to 3.4 Mb/s)
> +	 */
> +	if (dev->cfg.sm > I2C_FREQ_MODE_FAST) {
> +		dev_err(&dev->pdev->dev, "do not support this mode "
> +			"defaulting to std. mode\n");
> +		brcr2 = i2c_clk/(100000 * 2) & 0xffff;
> +		writel((brcr1 | brcr2), dev->virtbase + I2C_BRCR);
> +		writel(I2C_FREQ_MODE_STANDARD << I2C_CR_SM_POS,
> +				dev->virtbase + I2C_CR);
> +	}
> +	writel(dev->cfg.sm << I2C_CR_SM_POS, dev->virtbase + I2C_CR);
> +
> +	/* set the Tx and Rx FIFO threshold */
> +	writel(dev->cfg.tft, dev->virtbase + I2C_TFTR);
> +	writel(dev->cfg.rft, dev->virtbase + I2C_RFTR);
> +}
> +
> +/**
> + * read_i2c() - Read from I2C client device
> + * @dev: private data of I2C Driver
> + *
> + * This function reads from i2c client device when controller is in
> + * master mode. There is a completion timeout. If there is no transfer
> + * before timeout error is returned.
> + */
> +static int read_i2c(struct nmk_i2c_dev *dev)
> +{
> +	u32 status = 0;
> +	u32 mcr;
> +	u32 irq_mask = 0;
> +	int timeout;
> +
> +	mcr = load_i2c_mcr_reg(dev);
> +	writel(mcr, dev->virtbase + I2C_MCR);
> +
> +	/* load the current CR value */
> +	writel(readl(dev->virtbase + I2C_CR) | DEFAULT_I2C_REG_CR,
> +			dev->virtbase + I2C_CR);
> +
> +	/* enable the controller */
> +	i2c_set_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
> +
> +	init_completion(&dev->xfer_complete);
> +
> +	/* enable interrupts by setting the mask */
> +	irq_mask = (I2C_IT_RXFNF | I2C_IT_RXFF |
> +			I2C_IT_MAL | I2C_IT_BERR);
> +
> +	if (dev->stop)
> +		irq_mask |= I2C_IT_MTD;
> +	else
> +		irq_mask |= I2C_IT_MTDWS;
> +
> +	irq_mask = I2C_CLEAR_ALL_INTS & IRQ_MASK(irq_mask);
> +
> +	writel(readl(dev->virtbase + I2C_IMSCR) | irq_mask,
> +			dev->virtbase + I2C_IMSCR);
> +
> +	timeout = wait_for_completion_interruptible_timeout(
> +		&dev->xfer_complete, msecs_to_jiffies(I2C_TIMEOUT_MS));
> +
> +	if (timeout < 0) {
> +		dev_err(&dev->pdev->dev,
> +			"wait_for_completion_interruptible_timeout"
> +			"returned %d waiting for event\n", timeout);
> +		status = timeout;
> +	}
> +
> +	if (timeout == 0) {
> +		/* controler has timedout, re-init the h/w */
> +		dev_err(&dev->pdev->dev, "controller has timed out"
> +			"waiting for event, re-init h/w\n");
> +		(void) init_hw(dev);
> +		status = -ETIMEDOUT;
> +	}
> +
> +	return status;
> +}
> +
> +/**
> + * write_i2c() - Write data to I2C client.
> + * @dev: private data of I2C Driver
> + *
> + * This function writes data to I2C client
> + */
> +static int write_i2c(struct nmk_i2c_dev *dev)
> +{
> +	u32 status = 0;
> +	u32 mcr;
> +	u32 irq_mask = 0;
> +	int timeout;
> +
> +	mcr = load_i2c_mcr_reg(dev);
> +
> +	writel(mcr, dev->virtbase + I2C_MCR);
> +
> +	/* load the current CR value */
> +	writel(readl(dev->virtbase + I2C_CR) | DEFAULT_I2C_REG_CR,
> +			dev->virtbase + I2C_CR);
> +
> +	/* enable the controller */
> +	i2c_set_bit(dev->virtbase + I2C_CR , I2C_CR_PE);
> +
> +	init_completion(&dev->xfer_complete);
> +
> +	/* enable interrupts by settings the masks */
> +	irq_mask = (I2C_IT_TXFNE | I2C_IT_TXFOVR |
> +			I2C_IT_MAL | I2C_IT_BERR);
> +
> +	/*
> +	 * check if we want to transfer a single or multiple bytes, if so
> +	 * set the MTDWS bit (Master Transaction Done Without Stop)
> +	 * to start repeated start operation
> +	 */
> +	if (dev->stop)
> +		irq_mask |= I2C_IT_MTD;
> +	else
> +		irq_mask |= I2C_IT_MTDWS;
> +
> +	irq_mask = I2C_CLEAR_ALL_INTS & IRQ_MASK(irq_mask);
> +
> +	writel(readl(dev->virtbase + I2C_IMSCR) | irq_mask,
> +			dev->virtbase + I2C_IMSCR);
> +
> +	timeout = wait_for_completion_interruptible_timeout(
> +		&dev->xfer_complete, msecs_to_jiffies(I2C_TIMEOUT_MS));
> +
> +	if (timeout < 0) {
> +		dev_err(&dev->pdev->dev,
> +			"wait_for_completion_interruptible_timeout"
> +			"returned %d waiting for event\n", timeout);
> +		status = timeout;
> +	}
> +
> +	if (timeout == 0) {
> +		/* controler has timedout, re-init the h/w */
> +		dev_err(&dev->pdev->dev, "controller has timed out"
> +			"waiting for event, re-init h/w\n");

would prefer to see strings kept intact.

> +		(void) init_hw(dev);
> +		status = -ETIMEDOUT;
> +	}
> +
> +	return status;
> +}
> +
> +/**
> + * nmk_i2c_xfer() - I2C transfer function used by kernel framework
> + * @i2c_adap 	- Adapter pointer to the controller
> + * @msgs[] - Pointer to data to be written.
> + * @num_msgs - Number of messages to be executed
> + *
> + * This is the function called by the generic kernel i2c_transfer()
> + * or i2c_smbus...() API calls. Note that this code is protected by the
> + * semaphore set in the kernel i2c_transfer() function.
> + *
> + * NOTE:
> + * READ TRANSFER : We impose a restriction of the first message to be the
> + * 		index message for any read transaction.
> + * 		- a no index is coded as '0',
> + * 		- 2byte big endian index is coded as '3'
> + * 		!!! msg[0].buf holds the actual index.
> + * 		This is compatible with generic messages of smbus emulator
> + * 		that send a one byte index.
> + * 		eg. a I2C transation to read 2 bytes from index 0
> + *			idx = 0;
> + *			msg[0].addr = client->addr;
> + *			msg[0].flags = 0x0;
> + *			msg[0].len = 1;
> + *			msg[0].buf = &idx;
> + *
> + *			msg[1].addr = client->addr;
> + *			msg[1].flags = I2C_M_RD;
> + *			msg[1].len = 2;
> + *			msg[1].buf = rd_buff
> + *			i2c_transfer(adap, msg, 2);
> + *
> + * WRITE TRANSFER : The I2C standard interface interprets all data as payload.
> + *		If you want to emulate an SMBUS write transaction put the
> + *		index as first byte(or first and second) in the payload.
> + *		eg. a I2C transation to write 2 bytes from index 1
> + *			wr_buff[0] = 0x1;
> + *			wr_buff[1] = 0x23;
> + *			wr_buff[2] = 0x46;
> + *			msg[0].flags = 0x0;
> + *			msg[0].len = 3;
> + *			msg[0].buf = wr_buff;
> + *			i2c_transfer(adap, msg, 1);
> + *
> + * To read or write a block of data (multiple bytes) using SMBUS emulation
> + * please use the i2c_smbus_read_i2c_block_data()
> + * or i2c_smbus_write_i2c_block_data() API
> + *
> + * i2c_master_recv() API is not supported as single read message is not
> + * accepted by our interface (it has to be preceded by an index message)
> + */

Any reason for the restrictions? these seem a little harsh for anyone

> +static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
> +		struct i2c_msg msgs[], int num_msgs)
> +{
> +	int status;
> +	int i;
> +	u32 cause;
> +	struct nmk_i2c_dev *dev = i2c_get_adapdata(i2c_adap);
> +
> +	status = init_hw(dev);
> +	if (status)
> +		return status;
> +
> +	/* setup the i2c controller */
> +	setup_i2c_controller(dev);
> +
> +	for (i = 0; i < num_msgs; i++) {
> +		if (unlikely(msgs[i].flags & I2C_M_TEN)) {
> +			dev_err(&dev->pdev->dev, "10 bit addressing"
> +					"not supported\n");
> +			return -EINVAL;
> +		}
> +		dev->cli.slave_adr	= msgs[i].addr;
> +		dev->cli.buffer		= msgs[i].buf;
> +		dev->cli.count		= msgs[i].len;
> +		dev->stop = (i < (num_msgs - 1)) ? 0 : 1;
> +		dev->result = 0;
> +
> +		if (msgs[i].flags & I2C_M_RD) {
> +			/* it is a read operation */
> +			dev->cli.operation = I2C_READ;
> +			status = read_i2c(dev);
> +		} else {
> +			/* write operation */
> +			dev->cli.operation = I2C_WRITE;
> +			status = write_i2c(dev);
> +		}
> +		if (status || (dev->result)) {
> +			/* get the abort cause */
> +			cause =	(readl(dev->virtbase + I2C_SR) >> 4) & 0x7;
> +			dev_err(&dev->pdev->dev, "error during I2C"
> +					"message xfer: %d\n", cause);
> +			dev_err(&dev->pdev->dev, "%s\n",
> +				cause >= ARRAY_SIZE(abort_causes)
> +				? "unknown reason" : abort_causes[cause]);
> +			return status;
> +		}
> +		mdelay(1);
> +	}
> +	return status;
> +}
> +
> +/**
> + * disable_interrupts() - disable the interrupts
> + * @dev: private data of controller
> + */
> +static int disable_interrupts(struct nmk_i2c_dev *dev, u32 irq)
> +{
> +	irq = IRQ_MASK(irq);
> +	writel(readl(dev->virtbase + I2C_IMSCR) & ~(I2C_CLEAR_ALL_INTS & irq),
> +			dev->virtbase + I2C_IMSCR);
> +	return 0;
> +}
> +
> +/**
> + * i2c_irq_handler() - interrupt routine
> + * @irq: interrupt number
> + * @arg: data passed to the handler
> + *
> + * This is the interrupt handler for the i2c driver. Currently
> + * it handles the major interrupts like Rx & Tx FIFO management
> + * interrupts, master transaction interrupts, arbitration and
> + * bus error interrupts. The rest of the interrupts are treated as
> + * unhandled.
> + */
> +static irqreturn_t i2c_irq_handler(int irq, void *arg)
> +{
> +	struct nmk_i2c_dev *dev = arg;
> +	u32 tft, rft;
> +	u32 count;
> +	u32 misr;
> +	u32 src = 0;
> +
> +	/* load Tx FIFO and Rx FIFO threshold values */
> +	tft = readl(dev->virtbase + I2C_TFTR);
> +	rft = readl(dev->virtbase + I2C_RFTR);
> +
> +	/* read interrupt status register */
> +	misr = readl(dev->virtbase + I2C_MISR);
> +
> +	src = __ffs(misr);
> +	switch ((1 << src)) {
> +
> +	/* Transmit FIFO nearly empty interrupt */
> +	case I2C_IT_TXFNE:
> +	{
> +		if (dev->cli.operation == I2C_READ) {
> +			/*
> +			 * in read operation why do we care for writing?
> +			 * so disable the Transmit FIFO interrupt
> +			 */
> +			disable_interrupts(dev, I2C_IT_TXFNE);
> +		} else {
> +			for (count = (MAX_I2C_FIFO_THRESHOLD - tft - 2);
> +					(count > 0) &&
> +					(dev->cli.count != 0);
> +					count--) {
> +				/* write to the Tx FIFO */
> +				writeb(*dev->cli.buffer,
> +					dev->virtbase + I2C_TFR);
> +				dev->cli.buffer++;
> +				dev->cli.count--;
> +				dev->cli.xfer_bytes++;
> +			}
> +			/*
> +			 * if done, close the transfer by disabling the
> +			 * corresponding TXFNE interrupt
> +			 */
> +			if (dev->cli.count == 0)
> +				disable_interrupts(dev,	I2C_IT_TXFNE);
> +		}
> +	}
> +	break;
> +
> +	/*
> +	 * Rx FIFO nearly full interrupt.
> +	 * This is set when the numer of entries in Rx FIFO is
> +	 * greater or equal than the threshold value programmed
> +	 * in RFT
> +	 */
> +	case I2C_IT_RXFNF:
> +		for (count = rft; count > 0; count--) {
> +			/* Read the Rx FIFO */
> +			*dev->cli.buffer = readb(dev->virtbase + I2C_RFR);
> +			dev->cli.buffer++;
> +		}
> +		dev->cli.count -= rft;
> +		dev->cli.xfer_bytes += rft;
> +		break;
> +
> +	/* Rx FIFO full */
> +	case I2C_IT_RXFF:
> +		for (count = MAX_I2C_FIFO_THRESHOLD; count > 0; count--) {
> +			*dev->cli.buffer = readb(dev->virtbase + I2C_RFR);
> +			dev->cli.buffer++;
> +		}
> +		dev->cli.count -= MAX_I2C_FIFO_THRESHOLD;
> +		dev->cli.xfer_bytes += MAX_I2C_FIFO_THRESHOLD;
> +		break;
> +
> +	/* Master Transaction Done with/without stop */
> +	case I2C_IT_MTD:
> +	case I2C_IT_MTDWS:
> +		if (dev->cli.operation == I2C_READ) {
> +			while (!readl(dev->virtbase + I2C_RISR) & I2C_IT_RXFE) {
> +				if (dev->cli.count == 0)
> +					break;
> +				*dev->cli.buffer =
> +					readb(dev->virtbase + I2C_RFR);
> +				dev->cli.buffer++;
> +				dev->cli.count--;
> +				dev->cli.xfer_bytes++;
> +			}
> +		}
> +
> +		i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_MTD);
> +		i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_MTDWS);
> +
> +		disable_interrupts(dev,
> +				(I2C_IT_TXFNE | I2C_IT_TXFE | I2C_IT_TXFF
> +					| I2C_IT_TXFOVR | I2C_IT_RXFNF
> +					| I2C_IT_RXFF | I2C_IT_RXFE));
> +
> +		if (dev->cli.count) {
> +			dev->result = -1;
> +			dev_err(&dev->pdev->dev, "%lu bytes still remain to be"
> +					"xfered\n", dev->cli.count);
> +			(void) init_hw(dev);
> +		}
> +		complete(&dev->xfer_complete);
> +
> +		break;
> +
> +	/* Master Arbitration lost interrupt */
> +	case I2C_IT_MAL:
> +		dev->result = -1;
> +		(void) init_hw(dev);
> +
> +		i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_MAL);
> +		complete(&dev->xfer_complete);
> +
> +		break;
> +
> +	/*
> +	 * Bus Error interrupt.
> +	 * This happens when an unexpected start/stop condition occurs
> +	 * during the transaction.
> +	 */
> +	case I2C_IT_BERR:
> +		dev->result = -1;
> +		/* get the status */
> +		if (((readl(dev->virtbase + I2C_SR) >> 2) & 0x3) == I2C_ABORT)
> +			(void) init_hw(dev);
> +
> +		i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_BERR);
> +		complete(&dev->xfer_complete);
> +
> +		break;
> +
> +	/*
> +	 * Tx FIFO overrun interrupt.
> +	 * This is set when a write operation in Tx FIFO is performed and
> +	 * the Tx FIFO is full.
> +	 */
> +	case I2C_IT_TXFOVR:
> +		dev->result = -1;
> +		(void) init_hw(dev);
> +
> +		dev_err(&dev->pdev->dev, "Tx Fifo Over run\n");
> +		complete(&dev->xfer_complete);
> +
> +		break;
> +
> +	/* unhandled interrupts by this driver - TODO*/
> +	case I2C_IT_TXFE:
> +	case I2C_IT_TXFF:
> +	case I2C_IT_RXFE:
> +	case I2C_IT_RFSR:
> +	case I2C_IT_RFSE:
> +	case I2C_IT_WTSR:
> +	case I2C_IT_STD:
> +		dev_err(&dev->pdev->dev, "unhandled Interrupt\n");
> +		break;
> +	default:
> +		dev_err(&dev->pdev->dev, "spurious Interrupt..\n");
> +		break;
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int __init nmk_i2c_probe(struct platform_device *pdev)
> +{
> +	int ret = 0;
> +	struct resource *res;
> +	struct nmk_i2c_controller *pdata =
> +			pdev->dev.platform_data;
> +	struct nmk_i2c_dev	*dev;
> +	struct i2c_adapter *adap;
> +
> +	dev = kzalloc(sizeof(struct nmk_i2c_dev), GFP_KERNEL);
> +	if (!dev) {
> +		dev_err(&pdev->dev, "cannot allocate memory\n");
> +		ret = -ENOMEM;
> +		goto err_no_mem;
> +	}
> +
> +	dev->pdev = pdev;
> +	platform_set_drvdata(pdev, dev);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		ret = -ENOENT;
> +		goto err_no_resource;
> +	}
> +
> +	if (request_mem_region(res->start, resource_size(res),
> +		DRIVER_NAME "I/O region") == 	NULL)	{
> +		ret = -EBUSY;
> +		goto err_no_region;
> +	}
> +
> +	dev->virtbase = ioremap(res->start, resource_size(res));
> +	if (!dev->virtbase) {
> +		ret = -ENOMEM;
> +		goto err_no_ioremap;
> +	}
> +
> +	dev->irq = platform_get_irq(pdev, 0);
> +	ret = request_irq(dev->irq, i2c_irq_handler, IRQF_DISABLED,
> +				DRIVER_NAME, dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "cannot claim the irq %d\n", dev->irq);
> +		goto err_irq;
> +	}
> +
> +	dev->clk = clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(dev->clk)) {
> +		dev_err(&pdev->dev, "could not get i2c clock\n");
> +		ret = PTR_ERR(dev->clk);
> +		goto err_no_clk;
> +	}
> +
> +	clk_enable(dev->clk);
> +
> +	adap = &dev->adap;
> +	adap->dev.parent = &pdev->dev;
> +	adap->owner	= THIS_MODULE;
> +	adap->class	= I2C_CLASS_HWMON | I2C_CLASS_SPD;
> +	adap->algo	= &nmk_i2c_algo;
> +
> +	/* fetch the controller id */
> +	adap->nr	= pdev->id;
> +
> +	/* fetch the controller configuration from machine */
> +	dev->cfg.clk_freq = pdata->clk_freq;
> +	dev->cfg.slsu	= pdata->slsu;
> +	dev->cfg.tft	= pdata->tft;
> +	dev->cfg.rft	= pdata->rft;
> +	dev->cfg.sm	= pdata->sm;
> +
> +	i2c_set_adapdata(adap, dev);
> +
> +	ret = init_hw(dev);
> +	if (ret != 0) {
> +		dev_err(&pdev->dev, "error in initializing i2c hardware\n");
> +		goto err_init_hw;
> +	}
> +
> +	dev_dbg(&pdev->dev, "initialize I2C%d bus on virtual "
> +		"base %p\n", pdev->id, dev->virtbase);
> +
> +	ret = i2c_add_numbered_adapter(adap);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to add adapter\n");
> +		goto err_add_adap;
> +	}
> +
> +	return 0;
> +
> + err_init_hw:
> +	clk_disable(dev->clk);
> + err_add_adap:
> +	clk_put(dev->clk);
> + err_no_clk:
> +	free_irq(dev->irq, dev);
> + err_irq:
> +	iounmap(dev->virtbase);
> + err_no_ioremap:
> +	release_mem_region(res->start, resource_size(res));
> + err_no_region:
> +	platform_set_drvdata(pdev, NULL);
> + err_no_resource:
> +	kfree(dev);
> + err_no_mem:
> +
> +	return ret;
> +}
> +
> +static int __exit nmk_i2c_remove(struct platform_device *pdev)
> +{
> +	struct nmk_i2c_dev *dev = platform_get_drvdata(pdev);
> +
> +	i2c_del_adapter(&dev->adap);
> +	flush_i2c_fifo(dev);
> +	disable_all_interrupts(dev);
> +	clear_all_interrupts(dev);
> +	/* disable the controller */
> +	i2c_clr_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
> +	free_irq(dev->irq, dev);
> +	iounmap(dev->virtbase);
> +	clk_disable(dev->clk);
> +	clk_put(dev->clk);
> +	platform_set_drvdata(pdev, NULL);
> +	kfree(dev);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver nmk_i2c_driver = {
> +	.driver = {
> +		.owner = THIS_MODULE,
> +		.name = DRIVER_NAME,
> +	},
> +
> +	.probe = nmk_i2c_probe,
> +	.remove = __exit_p(nmk_i2c_remove),
__devexit_p remove should be __devexit.
> +};
> +
> +static int __init nmk_i2c_init(void)
> +{
> +	return platform_driver_register(&nmk_i2c_driver);
> +}
> +
> +static void __exit nmk_i2c_exit(void)
> +{
> +	platform_driver_unregister(&nmk_i2c_driver);
> +}
> +
> +subsys_initcall(nmk_i2c_init);
> +module_exit(nmk_i2c_exit);
> +
> +MODULE_AUTHOR("Sachin Verma, Srinidhi KASAGAR");
> +MODULE_DESCRIPTION("Nomadik/Ux500 I2C driver");
> +MODULE_LICENSE("GPL");

could do with a module alias field for the platform device.

> -- 
> 1.6.3.GIT
> 
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-- 
Ben (ben-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'