[PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[Nikolaus Voss]

The old driver has two main deficencies:
i)  No repeated start (Sr) condiction is possible, this makes it unusable
    e.g. for most SMBus transfers.
ii) I/O was done with polling/busy waiting what caused over-/underruns
    even at light system loads and clock speeds.

The new driver overcomes these deficencies and in addition allows for
more than one TWI interface.

A remaining limitation is the fact, that only one repeated start is
possible (two concatenated messages). This limitation is imposed by
the hardware. However, this should not be a problem as all common
i2c-client communication does not rely on more than one repeated start.

Changes since v11:
- corrected wrong id_entry on sam9261 twi gpio pdev

Nikolaus Voss (4):
  drivers/i2c/busses/i2c-at91.c: remove old polling driver
  Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
  drivers/i2c/busses/i2c-at91.c: add new driver
  G45 TWI: remove open drain setting for twi function gpios

 arch/arm/mach-at91/at91rm9200.c            |    1 +
 arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
 arch/arm/mach-at91/at91sam9260.c           |    1 +
 arch/arm/mach-at91/at91sam9261.c           |    1 +
 arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
 arch/arm/mach-at91/at91sam9263.c           |    1 +
 arch/arm/mach-at91/at91sam9g45.c           |    2 +
 arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
 arch/arm/mach-at91/at91sam9rl.c            |    2 +
 arch/arm/mach-at91/at91sam9x5.c            |    3 +
 arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
 drivers/i2c/busses/Kconfig                 |   11 +-
 drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
 13 files changed, 418 insertions(+), 287 deletions(-)
 delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h

-- 
1.7.9.5

[PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[Nikolaus Voss]

The old driver has two main deficencies:
i)  No repeated start (Sr) condiction is possible, this makes it unusable
    e.g. for most SMBus transfers.
ii) I/O was done with polling/busy waiting what caused over-/underruns
    even at light system loads and clock speeds.

The new driver overcomes these deficencies and in addition allows for
more than one TWI interface.

A remaining limitation is the fact, that only one repeated start is
possible (two concatenated messages). This limitation is imposed by
the hardware. However, this should not be a problem as all common
i2c-client communication does not rely on more than one repeated start.

Changes since v11:
- corrected wrong id_entry on sam9261 twi gpio pdev

Nikolaus Voss (4):
  drivers/i2c/busses/i2c-at91.c: remove old polling driver
  Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
  drivers/i2c/busses/i2c-at91.c: add new driver
  G45 TWI: remove open drain setting for twi function gpios

 arch/arm/mach-at91/at91rm9200.c            |    1 +
 arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
 arch/arm/mach-at91/at91sam9260.c           |    1 +
 arch/arm/mach-at91/at91sam9261.c           |    1 +
 arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
 arch/arm/mach-at91/at91sam9263.c           |    1 +
 arch/arm/mach-at91/at91sam9g45.c           |    2 +
 arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
 arch/arm/mach-at91/at91sam9rl.c            |    2 +
 arch/arm/mach-at91/at91sam9x5.c            |    3 +
 arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
 drivers/i2c/busses/Kconfig                 |   11 +-
 drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
 13 files changed, 418 insertions(+), 287 deletions(-)
 delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h

-- 
1.7.9.5

[PATCH v11 1/4] drivers/i2c/busses/i2c-at91.c: remove old polling driver

[Nikolaus Voss]

Signed-off-by: Nikolaus Voss <n.voss-+umVssTZoCsb1SvskN2V4Q@public.gmane.org>
---
 arch/arm/mach-at91/include/mach/at91_twi.h |   68 ------
 drivers/i2c/busses/Makefile                |    1 -
 drivers/i2c/busses/i2c-at91.c              |  314 ----------------------------
 3 files changed, 383 deletions(-)
 delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
 delete mode 100644 drivers/i2c/busses/i2c-at91.c

diff --git a/arch/arm/mach-at91/include/mach/at91_twi.h b/arch/arm/mach-at91/include/mach/at91_twi.h
deleted file mode 100644
index bb2880f..0000000
--- a/arch/arm/mach-at91/include/mach/at91_twi.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * arch/arm/mach-at91/include/mach/at91_twi.h
- *
- * Copyright (C) 2005 Ivan Kokshaysky
- * Copyright (C) SAN People
- *
- * Two-wire Interface (TWI) registers.
- * Based on AT91RM9200 datasheet revision E.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- */
-
-#ifndef AT91_TWI_H
-#define AT91_TWI_H
-
-#define	AT91_TWI_CR		0x00		/* Control Register */
-#define		AT91_TWI_START		(1 <<  0)	/* Send a Start Condition */
-#define		AT91_TWI_STOP		(1 <<  1)	/* Send a Stop Condition */
-#define		AT91_TWI_MSEN		(1 <<  2)	/* Master Transfer Enable */
-#define		AT91_TWI_MSDIS		(1 <<  3)	/* Master Transfer Disable */
-#define		AT91_TWI_SVEN		(1 <<  4)	/* Slave Transfer Enable [SAM9260 only] */
-#define		AT91_TWI_SVDIS		(1 <<  5)	/* Slave Transfer Disable [SAM9260 only] */
-#define		AT91_TWI_SWRST		(1 <<  7)	/* Software Reset */
-
-#define	AT91_TWI_MMR		0x04		/* Master Mode Register */
-#define		AT91_TWI_IADRSZ		(3    <<  8)	/* Internal Device Address Size */
-#define			AT91_TWI_IADRSZ_NO		(0 << 8)
-#define			AT91_TWI_IADRSZ_1		(1 << 8)
-#define			AT91_TWI_IADRSZ_2		(2 << 8)
-#define			AT91_TWI_IADRSZ_3		(3 << 8)
-#define		AT91_TWI_MREAD		(1    << 12)	/* Master Read Direction */
-#define		AT91_TWI_DADR		(0x7f << 16)	/* Device Address */
-
-#define	AT91_TWI_SMR		0x08		/* Slave Mode Register [SAM9260 only] */
-#define		AT91_TWI_SADR		(0x7f << 16)	/* Slave Address */
-
-#define	AT91_TWI_IADR		0x0c		/* Internal Address Register */
-
-#define	AT91_TWI_CWGR		0x10		/* Clock Waveform Generator Register */
-#define		AT91_TWI_CLDIV		(0xff <<  0)	/* Clock Low Divisor */
-#define		AT91_TWI_CHDIV		(0xff <<  8)	/* Clock High Divisor */
-#define		AT91_TWI_CKDIV		(7    << 16)	/* Clock Divider */
-
-#define	AT91_TWI_SR		0x20		/* Status Register */
-#define		AT91_TWI_TXCOMP		(1 <<  0)	/* Transmission Complete */
-#define		AT91_TWI_RXRDY		(1 <<  1)	/* Receive Holding Register Ready */
-#define		AT91_TWI_TXRDY		(1 <<  2)	/* Transmit Holding Register Ready */
-#define		AT91_TWI_SVREAD		(1 <<  3)	/* Slave Read [SAM9260 only] */
-#define		AT91_TWI_SVACC		(1 <<  4)	/* Slave Access [SAM9260 only] */
-#define		AT91_TWI_GACC		(1 <<  5)	/* General Call Access [SAM9260 only] */
-#define		AT91_TWI_OVRE		(1 <<  6)	/* Overrun Error [AT91RM9200 only] */
-#define		AT91_TWI_UNRE		(1 <<  7)	/* Underrun Error [AT91RM9200 only] */
-#define		AT91_TWI_NACK		(1 <<  8)	/* Not Acknowledged */
-#define		AT91_TWI_ARBLST		(1 <<  9)	/* Arbitration Lost [SAM9260 only] */
-#define		AT91_TWI_SCLWS		(1 << 10)	/* Clock Wait State [SAM9260 only] */
-#define		AT91_TWI_EOSACC		(1 << 11)	/* End of Slave Address [SAM9260 only] */
-
-#define	AT91_TWI_IER		0x24		/* Interrupt Enable Register */
-#define	AT91_TWI_IDR		0x28		/* Interrupt Disable Register */
-#define	AT91_TWI_IMR		0x2c		/* Interrupt Mask Register */
-#define	AT91_TWI_RHR		0x30		/* Receive Holding Register */
-#define	AT91_TWI_THR		0x34		/* Transmit Holding Register */
-
-#endif
-
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index ce3c2be..4f46873 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -28,7 +28,6 @@ obj-$(CONFIG_I2C_HYDRA)		+= i2c-hydra.o
 obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 
 # Embedded system I2C/SMBus host controller drivers
-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_CPM)		+= i2c-cpm.o
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
deleted file mode 100644
index 1679dee..0000000
--- a/drivers/i2c/busses/i2c-at91.c
+++ /dev/null
@@ -1,314 +0,0 @@
-/*
-    i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
-
-    Copyright (C) 2004 Rick Bronson
-    Converted to 2.6 by Andrew Victor <andrew-eS41wJS13H5l57MIdRCFDg@public.gmane.org>
-
-    Borrowed heavily from original work by:
-    Copyright (C) 2000 Philip Edelbrock <phil-LT64U7CwzWEZMC/lefXSXFaTQe2KTcn/@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 as published by
-    the Free Software Foundation; either version 2 of the License, or
-    (at your option) any later version.
-*/
-
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/err.h>
-#include <linux/slab.h>
-#include <linux/types.h>
-#include <linux/delay.h>
-#include <linux/i2c.h>
-#include <linux/init.h>
-#include <linux/clk.h>
-#include <linux/platform_device.h>
-#include <linux/io.h>
-
-#include <mach/at91_twi.h>
-#include <mach/board.h>
-#include <mach/cpu.h>
-
-#define TWI_CLOCK		100000		/* Hz. max 400 Kbits/sec */
-
-
-static struct clk *twi_clk;
-static void __iomem *twi_base;
-
-#define at91_twi_read(reg)		__raw_readl(twi_base + (reg))
-#define at91_twi_write(reg, val)	__raw_writel((val), twi_base + (reg))
-
-
-/*
- * Initialize the TWI hardware registers.
- */
-static void __devinit at91_twi_hwinit(void)
-{
-	unsigned long cdiv, ckdiv;
-
-	at91_twi_write(AT91_TWI_IDR, 0xffffffff);	/* Disable all interrupts */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_SWRST);	/* Reset peripheral */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_MSEN);	/* Set Master mode */
-
-	/* Calcuate clock dividers */
-	cdiv = (clk_get_rate(twi_clk) / (2 * TWI_CLOCK)) - 3;
-	cdiv = cdiv + 1;	/* round up */
-	ckdiv = 0;
-	while (cdiv > 255) {
-		ckdiv++;
-		cdiv = cdiv >> 1;
-	}
-
-	if (cpu_is_at91rm9200()) {			/* AT91RM9200 Errata #22 */
-		if (ckdiv > 5) {
-			printk(KERN_ERR "AT91 I2C: Invalid TWI_CLOCK value!\n");
-			ckdiv = 5;
-		}
-	}
-
-	at91_twi_write(AT91_TWI_CWGR, (ckdiv << 16) | (cdiv << 8) | cdiv);
-}
-
-/*
- * Poll the i2c status register until the specified bit is set.
- * Returns 0 if timed out (100 msec).
- */
-static short at91_poll_status(unsigned long bit)
-{
-	int loop_cntr = 10000;
-
-	do {
-		udelay(10);
-	} while (!(at91_twi_read(AT91_TWI_SR) & bit) && (--loop_cntr > 0));
-
-	return (loop_cntr > 0);
-}
-
-static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length)
-{
-	/* Send Start */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
-
-	/* Read data */
-	while (length--) {
-		if (!length)	/* need to send Stop before reading last byte */
-			at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);
-		if (!at91_poll_status(AT91_TWI_RXRDY)) {
-			dev_dbg(&adap->dev, "RXRDY timeout\n");
-			return -ETIMEDOUT;
-		}
-		*buf++ = (at91_twi_read(AT91_TWI_RHR) & 0xff);
-	}
-
-	return 0;
-}
-
-static int xfer_write(struct i2c_adapter *adap, unsigned char *buf, int length)
-{
-	/* Load first byte into transmitter */
-	at91_twi_write(AT91_TWI_THR, *buf++);
-
-	/* Send Start */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
-
-	do {
-		if (!at91_poll_status(AT91_TWI_TXRDY)) {
-			dev_dbg(&adap->dev, "TXRDY timeout\n");
-			return -ETIMEDOUT;
-		}
-
-		length--;	/* byte was transmitted */
-
-		if (length > 0)		/* more data to send? */
-			at91_twi_write(AT91_TWI_THR, *buf++);
-	} while (length);
-
-	/* Send Stop */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);
-
-	return 0;
-}
-
-/*
- * Generic i2c master transfer entrypoint.
- *
- * Note: We do not use Atmel's feature of storing the "internal device address".
- * Instead the "internal device address" has to be written using a separate
- * i2c message.
- * http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-September/024411.html
- */
-static int at91_xfer(struct i2c_adapter *adap, struct i2c_msg *pmsg, int num)
-{
-	int i, ret;
-
-	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
-
-	for (i = 0; i < num; i++) {
-		dev_dbg(&adap->dev, " #%d: %sing %d byte%s %s 0x%02x\n", i,
-			pmsg->flags & I2C_M_RD ? "read" : "writ",
-			pmsg->len, pmsg->len > 1 ? "s" : "",
-			pmsg->flags & I2C_M_RD ? "from" : "to",	pmsg->addr);
-
-		at91_twi_write(AT91_TWI_MMR, (pmsg->addr << 16)
-			| ((pmsg->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0));
-
-		if (pmsg->len && pmsg->buf) {	/* sanity check */
-			if (pmsg->flags & I2C_M_RD)
-				ret = xfer_read(adap, pmsg->buf, pmsg->len);
-			else
-				ret = xfer_write(adap, pmsg->buf, pmsg->len);
-
-			if (ret)
-				return ret;
-
-			/* Wait until transfer is finished */
-			if (!at91_poll_status(AT91_TWI_TXCOMP)) {
-				dev_dbg(&adap->dev, "TXCOMP timeout\n");
-				return -ETIMEDOUT;
-			}
-		}
-		dev_dbg(&adap->dev, "transfer complete\n");
-		pmsg++;		/* next message */
-	}
-	return i;
-}
-
-/*
- * Return list of supported functionality.
- */
-static u32 at91_func(struct i2c_adapter *adapter)
-{
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
-}
-
-static struct i2c_algorithm at91_algorithm = {
-	.master_xfer	= at91_xfer,
-	.functionality	= at91_func,
-};
-
-/*
- * Main initialization routine.
- */
-static int __devinit at91_i2c_probe(struct platform_device *pdev)
-{
-	struct i2c_adapter *adapter;
-	struct resource *res;
-	int rc;
-
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res)
-		return -ENXIO;
-
-	if (!request_mem_region(res->start, resource_size(res), "at91_i2c"))
-		return -EBUSY;
-
-	twi_base = ioremap(res->start, resource_size(res));
-	if (!twi_base) {
-		rc = -ENOMEM;
-		goto fail0;
-	}
-
-	twi_clk = clk_get(NULL, "twi_clk");
-	if (IS_ERR(twi_clk)) {
-		dev_err(&pdev->dev, "no clock defined\n");
-		rc = -ENODEV;
-		goto fail1;
-	}
-
-	adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
-	if (adapter == NULL) {
-		dev_err(&pdev->dev, "can't allocate inteface!\n");
-		rc = -ENOMEM;
-		goto fail2;
-	}
-	snprintf(adapter->name, sizeof(adapter->name), "AT91");
-	adapter->algo = &at91_algorithm;
-	adapter->class = I2C_CLASS_HWMON;
-	adapter->dev.parent = &pdev->dev;
-	/* adapter->id == 0 ... only one TWI controller for now */
-
-	platform_set_drvdata(pdev, adapter);
-
-	clk_enable(twi_clk);		/* enable peripheral clock */
-	at91_twi_hwinit();		/* initialize TWI controller */
-
-	rc = i2c_add_numbered_adapter(adapter);
-	if (rc) {
-		dev_err(&pdev->dev, "Adapter %s registration failed\n",
-				adapter->name);
-		goto fail3;
-	}
-
-	dev_info(&pdev->dev, "AT91 i2c bus driver.\n");
-	return 0;
-
-fail3:
-	platform_set_drvdata(pdev, NULL);
-	kfree(adapter);
-	clk_disable(twi_clk);
-fail2:
-	clk_put(twi_clk);
-fail1:
-	iounmap(twi_base);
-fail0:
-	release_mem_region(res->start, resource_size(res));
-
-	return rc;
-}
-
-static int __devexit at91_i2c_remove(struct platform_device *pdev)
-{
-	struct i2c_adapter *adapter = platform_get_drvdata(pdev);
-	struct resource *res;
-	int rc;
-
-	rc = i2c_del_adapter(adapter);
-	platform_set_drvdata(pdev, NULL);
-
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	iounmap(twi_base);
-	release_mem_region(res->start, resource_size(res));
-
-	clk_disable(twi_clk);		/* disable peripheral clock */
-	clk_put(twi_clk);
-
-	return rc;
-}
-
-#ifdef CONFIG_PM
-
-/* NOTE: could save a few mA by keeping clock off outside of at91_xfer... */
-
-static int at91_i2c_suspend(struct platform_device *pdev, pm_message_t mesg)
-{
-	clk_disable(twi_clk);
-	return 0;
-}
-
-static int at91_i2c_resume(struct platform_device *pdev)
-{
-	return clk_enable(twi_clk);
-}
-
-#else
-#define at91_i2c_suspend	NULL
-#define at91_i2c_resume		NULL
-#endif
-
-static struct platform_driver at91_i2c_driver = {
-	.probe		= at91_i2c_probe,
-	.remove		= __devexit_p(at91_i2c_remove),
-	.suspend	= at91_i2c_suspend,
-	.resume		= at91_i2c_resume,
-	.driver		= {
-		.name	= "at91_i2c",
-		.owner	= THIS_MODULE,
-	},
-};
-
-module_platform_driver(at91_i2c_driver);
-
-MODULE_AUTHOR("Rick Bronson");
-MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("platform:at91_i2c");
-- 
1.7.9.5

[PATCH v11 1/4] drivers/i2c/busses/i2c-at91.c: remove old polling driver

[Nikolaus Voss]

Signed-off-by: Nikolaus Voss <n.voss@weinmann.de>
---
 arch/arm/mach-at91/include/mach/at91_twi.h |   68 ------
 drivers/i2c/busses/Makefile                |    1 -
 drivers/i2c/busses/i2c-at91.c              |  314 ----------------------------
 3 files changed, 383 deletions(-)
 delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
 delete mode 100644 drivers/i2c/busses/i2c-at91.c

diff --git a/arch/arm/mach-at91/include/mach/at91_twi.h b/arch/arm/mach-at91/include/mach/at91_twi.h
deleted file mode 100644
index bb2880f..0000000
--- a/arch/arm/mach-at91/include/mach/at91_twi.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * arch/arm/mach-at91/include/mach/at91_twi.h
- *
- * Copyright (C) 2005 Ivan Kokshaysky
- * Copyright (C) SAN People
- *
- * Two-wire Interface (TWI) registers.
- * Based on AT91RM9200 datasheet revision E.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- */
-
-#ifndef AT91_TWI_H
-#define AT91_TWI_H
-
-#define	AT91_TWI_CR		0x00		/* Control Register */
-#define		AT91_TWI_START		(1 <<  0)	/* Send a Start Condition */
-#define		AT91_TWI_STOP		(1 <<  1)	/* Send a Stop Condition */
-#define		AT91_TWI_MSEN		(1 <<  2)	/* Master Transfer Enable */
-#define		AT91_TWI_MSDIS		(1 <<  3)	/* Master Transfer Disable */
-#define		AT91_TWI_SVEN		(1 <<  4)	/* Slave Transfer Enable [SAM9260 only] */
-#define		AT91_TWI_SVDIS		(1 <<  5)	/* Slave Transfer Disable [SAM9260 only] */
-#define		AT91_TWI_SWRST		(1 <<  7)	/* Software Reset */
-
-#define	AT91_TWI_MMR		0x04		/* Master Mode Register */
-#define		AT91_TWI_IADRSZ		(3    <<  8)	/* Internal Device Address Size */
-#define			AT91_TWI_IADRSZ_NO		(0 << 8)
-#define			AT91_TWI_IADRSZ_1		(1 << 8)
-#define			AT91_TWI_IADRSZ_2		(2 << 8)
-#define			AT91_TWI_IADRSZ_3		(3 << 8)
-#define		AT91_TWI_MREAD		(1    << 12)	/* Master Read Direction */
-#define		AT91_TWI_DADR		(0x7f << 16)	/* Device Address */
-
-#define	AT91_TWI_SMR		0x08		/* Slave Mode Register [SAM9260 only] */
-#define		AT91_TWI_SADR		(0x7f << 16)	/* Slave Address */
-
-#define	AT91_TWI_IADR		0x0c		/* Internal Address Register */
-
-#define	AT91_TWI_CWGR		0x10		/* Clock Waveform Generator Register */
-#define		AT91_TWI_CLDIV		(0xff <<  0)	/* Clock Low Divisor */
-#define		AT91_TWI_CHDIV		(0xff <<  8)	/* Clock High Divisor */
-#define		AT91_TWI_CKDIV		(7    << 16)	/* Clock Divider */
-
-#define	AT91_TWI_SR		0x20		/* Status Register */
-#define		AT91_TWI_TXCOMP		(1 <<  0)	/* Transmission Complete */
-#define		AT91_TWI_RXRDY		(1 <<  1)	/* Receive Holding Register Ready */
-#define		AT91_TWI_TXRDY		(1 <<  2)	/* Transmit Holding Register Ready */
-#define		AT91_TWI_SVREAD		(1 <<  3)	/* Slave Read [SAM9260 only] */
-#define		AT91_TWI_SVACC		(1 <<  4)	/* Slave Access [SAM9260 only] */
-#define		AT91_TWI_GACC		(1 <<  5)	/* General Call Access [SAM9260 only] */
-#define		AT91_TWI_OVRE		(1 <<  6)	/* Overrun Error [AT91RM9200 only] */
-#define		AT91_TWI_UNRE		(1 <<  7)	/* Underrun Error [AT91RM9200 only] */
-#define		AT91_TWI_NACK		(1 <<  8)	/* Not Acknowledged */
-#define		AT91_TWI_ARBLST		(1 <<  9)	/* Arbitration Lost [SAM9260 only] */
-#define		AT91_TWI_SCLWS		(1 << 10)	/* Clock Wait State [SAM9260 only] */
-#define		AT91_TWI_EOSACC		(1 << 11)	/* End of Slave Address [SAM9260 only] */
-
-#define	AT91_TWI_IER		0x24		/* Interrupt Enable Register */
-#define	AT91_TWI_IDR		0x28		/* Interrupt Disable Register */
-#define	AT91_TWI_IMR		0x2c		/* Interrupt Mask Register */
-#define	AT91_TWI_RHR		0x30		/* Receive Holding Register */
-#define	AT91_TWI_THR		0x34		/* Transmit Holding Register */
-
-#endif
-
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index ce3c2be..4f46873 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -28,7 +28,6 @@ obj-$(CONFIG_I2C_HYDRA)		+= i2c-hydra.o
 obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 
 # Embedded system I2C/SMBus host controller drivers
-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_CPM)		+= i2c-cpm.o
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
deleted file mode 100644
index 1679dee..0000000
--- a/drivers/i2c/busses/i2c-at91.c
+++ /dev/null
@@ -1,314 +0,0 @@
-/*
-    i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
-
-    Copyright (C) 2004 Rick Bronson
-    Converted to 2.6 by Andrew Victor <andrew@sanpeople.com>
-
-    Borrowed heavily from original work by:
-    Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
-
-    This program is free software; you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation; either version 2 of the License, or
-    (at your option) any later version.
-*/
-
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/err.h>
-#include <linux/slab.h>
-#include <linux/types.h>
-#include <linux/delay.h>
-#include <linux/i2c.h>
-#include <linux/init.h>
-#include <linux/clk.h>
-#include <linux/platform_device.h>
-#include <linux/io.h>
-
-#include <mach/at91_twi.h>
-#include <mach/board.h>
-#include <mach/cpu.h>
-
-#define TWI_CLOCK		100000		/* Hz. max 400 Kbits/sec */
-
-
-static struct clk *twi_clk;
-static void __iomem *twi_base;
-
-#define at91_twi_read(reg)		__raw_readl(twi_base + (reg))
-#define at91_twi_write(reg, val)	__raw_writel((val), twi_base + (reg))
-
-
-/*
- * Initialize the TWI hardware registers.
- */
-static void __devinit at91_twi_hwinit(void)
-{
-	unsigned long cdiv, ckdiv;
-
-	at91_twi_write(AT91_TWI_IDR, 0xffffffff);	/* Disable all interrupts */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_SWRST);	/* Reset peripheral */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_MSEN);	/* Set Master mode */
-
-	/* Calcuate clock dividers */
-	cdiv = (clk_get_rate(twi_clk) / (2 * TWI_CLOCK)) - 3;
-	cdiv = cdiv + 1;	/* round up */
-	ckdiv = 0;
-	while (cdiv > 255) {
-		ckdiv++;
-		cdiv = cdiv >> 1;
-	}
-
-	if (cpu_is_at91rm9200()) {			/* AT91RM9200 Errata #22 */
-		if (ckdiv > 5) {
-			printk(KERN_ERR "AT91 I2C: Invalid TWI_CLOCK value!\n");
-			ckdiv = 5;
-		}
-	}
-
-	at91_twi_write(AT91_TWI_CWGR, (ckdiv << 16) | (cdiv << 8) | cdiv);
-}
-
-/*
- * Poll the i2c status register until the specified bit is set.
- * Returns 0 if timed out (100 msec).
- */
-static short at91_poll_status(unsigned long bit)
-{
-	int loop_cntr = 10000;
-
-	do {
-		udelay(10);
-	} while (!(at91_twi_read(AT91_TWI_SR) & bit) && (--loop_cntr > 0));
-
-	return (loop_cntr > 0);
-}
-
-static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length)
-{
-	/* Send Start */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
-
-	/* Read data */
-	while (length--) {
-		if (!length)	/* need to send Stop before reading last byte */
-			at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);
-		if (!at91_poll_status(AT91_TWI_RXRDY)) {
-			dev_dbg(&adap->dev, "RXRDY timeout\n");
-			return -ETIMEDOUT;
-		}
-		*buf++ = (at91_twi_read(AT91_TWI_RHR) & 0xff);
-	}
-
-	return 0;
-}
-
-static int xfer_write(struct i2c_adapter *adap, unsigned char *buf, int length)
-{
-	/* Load first byte into transmitter */
-	at91_twi_write(AT91_TWI_THR, *buf++);
-
-	/* Send Start */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
-
-	do {
-		if (!at91_poll_status(AT91_TWI_TXRDY)) {
-			dev_dbg(&adap->dev, "TXRDY timeout\n");
-			return -ETIMEDOUT;
-		}
-
-		length--;	/* byte was transmitted */
-
-		if (length > 0)		/* more data to send? */
-			at91_twi_write(AT91_TWI_THR, *buf++);
-	} while (length);
-
-	/* Send Stop */
-	at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);
-
-	return 0;
-}
-
-/*
- * Generic i2c master transfer entrypoint.
- *
- * Note: We do not use Atmel's feature of storing the "internal device address".
- * Instead the "internal device address" has to be written using a separate
- * i2c message.
- * http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-September/024411.html
- */
-static int at91_xfer(struct i2c_adapter *adap, struct i2c_msg *pmsg, int num)
-{
-	int i, ret;
-
-	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
-
-	for (i = 0; i < num; i++) {
-		dev_dbg(&adap->dev, " #%d: %sing %d byte%s %s 0x%02x\n", i,
-			pmsg->flags & I2C_M_RD ? "read" : "writ",
-			pmsg->len, pmsg->len > 1 ? "s" : "",
-			pmsg->flags & I2C_M_RD ? "from" : "to",	pmsg->addr);
-
-		at91_twi_write(AT91_TWI_MMR, (pmsg->addr << 16)
-			| ((pmsg->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0));
-
-		if (pmsg->len && pmsg->buf) {	/* sanity check */
-			if (pmsg->flags & I2C_M_RD)
-				ret = xfer_read(adap, pmsg->buf, pmsg->len);
-			else
-				ret = xfer_write(adap, pmsg->buf, pmsg->len);
-
-			if (ret)
-				return ret;
-
-			/* Wait until transfer is finished */
-			if (!at91_poll_status(AT91_TWI_TXCOMP)) {
-				dev_dbg(&adap->dev, "TXCOMP timeout\n");
-				return -ETIMEDOUT;
-			}
-		}
-		dev_dbg(&adap->dev, "transfer complete\n");
-		pmsg++;		/* next message */
-	}
-	return i;
-}
-
-/*
- * Return list of supported functionality.
- */
-static u32 at91_func(struct i2c_adapter *adapter)
-{
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
-}
-
-static struct i2c_algorithm at91_algorithm = {
-	.master_xfer	= at91_xfer,
-	.functionality	= at91_func,
-};
-
-/*
- * Main initialization routine.
- */
-static int __devinit at91_i2c_probe(struct platform_device *pdev)
-{
-	struct i2c_adapter *adapter;
-	struct resource *res;
-	int rc;
-
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res)
-		return -ENXIO;
-
-	if (!request_mem_region(res->start, resource_size(res), "at91_i2c"))
-		return -EBUSY;
-
-	twi_base = ioremap(res->start, resource_size(res));
-	if (!twi_base) {
-		rc = -ENOMEM;
-		goto fail0;
-	}
-
-	twi_clk = clk_get(NULL, "twi_clk");
-	if (IS_ERR(twi_clk)) {
-		dev_err(&pdev->dev, "no clock defined\n");
-		rc = -ENODEV;
-		goto fail1;
-	}
-
-	adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
-	if (adapter == NULL) {
-		dev_err(&pdev->dev, "can't allocate inteface!\n");
-		rc = -ENOMEM;
-		goto fail2;
-	}
-	snprintf(adapter->name, sizeof(adapter->name), "AT91");
-	adapter->algo = &at91_algorithm;
-	adapter->class = I2C_CLASS_HWMON;
-	adapter->dev.parent = &pdev->dev;
-	/* adapter->id == 0 ... only one TWI controller for now */
-
-	platform_set_drvdata(pdev, adapter);
-
-	clk_enable(twi_clk);		/* enable peripheral clock */
-	at91_twi_hwinit();		/* initialize TWI controller */
-
-	rc = i2c_add_numbered_adapter(adapter);
-	if (rc) {
-		dev_err(&pdev->dev, "Adapter %s registration failed\n",
-				adapter->name);
-		goto fail3;
-	}
-
-	dev_info(&pdev->dev, "AT91 i2c bus driver.\n");
-	return 0;
-
-fail3:
-	platform_set_drvdata(pdev, NULL);
-	kfree(adapter);
-	clk_disable(twi_clk);
-fail2:
-	clk_put(twi_clk);
-fail1:
-	iounmap(twi_base);
-fail0:
-	release_mem_region(res->start, resource_size(res));
-
-	return rc;
-}
-
-static int __devexit at91_i2c_remove(struct platform_device *pdev)
-{
-	struct i2c_adapter *adapter = platform_get_drvdata(pdev);
-	struct resource *res;
-	int rc;
-
-	rc = i2c_del_adapter(adapter);
-	platform_set_drvdata(pdev, NULL);
-
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	iounmap(twi_base);
-	release_mem_region(res->start, resource_size(res));
-
-	clk_disable(twi_clk);		/* disable peripheral clock */
-	clk_put(twi_clk);
-
-	return rc;
-}
-
-#ifdef CONFIG_PM
-
-/* NOTE: could save a few mA by keeping clock off outside of at91_xfer... */
-
-static int at91_i2c_suspend(struct platform_device *pdev, pm_message_t mesg)
-{
-	clk_disable(twi_clk);
-	return 0;
-}
-
-static int at91_i2c_resume(struct platform_device *pdev)
-{
-	return clk_enable(twi_clk);
-}
-
-#else
-#define at91_i2c_suspend	NULL
-#define at91_i2c_resume		NULL
-#endif
-
-static struct platform_driver at91_i2c_driver = {
-	.probe		= at91_i2c_probe,
-	.remove		= __devexit_p(at91_i2c_remove),
-	.suspend	= at91_i2c_suspend,
-	.resume		= at91_i2c_resume,
-	.driver		= {
-		.name	= "at91_i2c",
-		.owner	= THIS_MODULE,
-	},
-};
-
-module_platform_driver(at91_i2c_driver);
-
-MODULE_AUTHOR("Rick Bronson");
-MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("platform:at91_i2c");
-- 
1.7.9.5

[PATCH v11 3/4] drivers/i2c/busses/i2c-at91.c: add new driver

[Nikolaus Voss]

This driver has the following properties compared to the old driver:
1. Support for multiple interfaces.
2. Interrupt driven I/O as opposed to polling/busy waiting.
3. Support for _one_ repeated start (Sr) condition, which is enough
   for most real-world applications including all SMBus transfer types.
   (The hardware does not support issuing arbitrary Sr conditions on the
    bus.)

testing: SoC: at91sam9g45
	 - BQ20Z80 battery SMBus client.
	 - on a 2.6.38 kernel with several i2c clients (temp-sensor,
	   audio-codec, touchscreen-controller, w1-bridge, io-expanders)

Signed-off-by: Nikolaus Voss <n.voss-+umVssTZoCsb1SvskN2V4Q@public.gmane.org>
Reviewed-by: Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>
Tested-by: Hubert Feurstein <h.feurstein-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

v12: - corrected wrong id_entry on sam9261 twi gpio pdev
v11: - fix for flags persistency suggested by Carsten Behling
     - calc_twi_clock fix for sam9261 by Ludovic Desroches
v10: - applied fix for RXRDY overrun bug submitted by Hubert Feurstein
     - applied fix for calculating twi_clk
v9: - merge i2c-at91.c patches to single patch
    - rewrite cwgr reg after timeout
v8: - remove local include
    - remove cpu_is_rm9200() and put twi hw bug info in platform_device
    - use readl/writel_relaxed instead of __raw_readl/writel
v7: i)  fix bug if internal address > 1 byte
    ii) send stop when len == 1 (both reported by Carsten Behling)
v6: support for I2C_SMBUS_BLOCK_DATA transfers.
    Better use of clk_(un)prepare().
    More sensible transfer timeout.
v5: Another round of review comments from Ryan Mallon, Felipe Balbi
    and Russell King: convert twi clk to use .dev_id, cleanups
v4: Integrated more review comments from Ryan Mallon and Felipe Balbi:
    Moved register include file to local include, code cleanups
v3: Integrated review comments from Ryan Mallon and Felipe Balbi
v2: Fixed whitespace issue
---
 arch/arm/mach-at91/at91rm9200_devices.c  |    9 +
 arch/arm/mach-at91/at91sam9261_devices.c |    9 +
 drivers/i2c/busses/Kconfig               |   11 +-
 drivers/i2c/busses/Makefile              |    1 +
 drivers/i2c/busses/i2c-at91.c            |  493 ++++++++++++++++++++++++++++++
 5 files changed, 516 insertions(+), 7 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-at91.c

diff --git a/arch/arm/mach-at91/at91rm9200_devices.c b/arch/arm/mach-at91/at91rm9200_devices.c
index e6b7d05..2977a2d 100644
--- a/arch/arm/mach-at91/at91rm9200_devices.c
+++ b/arch/arm/mach-at91/at91rm9200_devices.c
@@ -494,9 +494,18 @@ static struct resource twi_resources[] = {
 	},
 };
 
+static const struct platform_device_id twi_ip_type = {
+	/*
+	 * driver_data is 1 for RM9200 compatible ip, see enum twi_ip_id in
+	 * drivers/i2c/busses/i2c-at91.c
+	 */
+	.driver_data	= 1,
+};
+
 static struct platform_device at91rm9200_twi_device = {
 	.name		= "at91_i2c",
 	.id		= -1,
+	.id_entry	= &twi_ip_type,
 	.resource	= twi_resources,
 	.num_resources	= ARRAY_SIZE(twi_resources),
 };
diff --git a/arch/arm/mach-at91/at91sam9261_devices.c b/arch/arm/mach-at91/at91sam9261_devices.c
index 9295e90..aeb2eed 100644
--- a/arch/arm/mach-at91/at91sam9261_devices.c
+++ b/arch/arm/mach-at91/at91sam9261_devices.c
@@ -316,9 +316,18 @@ static struct resource twi_resources[] = {
 	},
 };
 
+static const struct platform_device_id twi_ip_type = {
+	/*
+	 * driver_data is 2 for SAM9261 compatible ip, see enum twi_ip_id in
+	 * drivers/i2c/busses/i2c-at91.c
+	 */
+	.driver_data	= 2,
+};
+
 static struct platform_device at91sam9261_twi_device = {
 	.name		= "at91_i2c",
 	.id		= -1,
+	.id_entry	= &twi_ip_type,
 	.resource	= twi_resources,
 	.num_resources	= ARRAY_SIZE(twi_resources),
 };
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 7244c8b..6b74287 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -286,18 +286,15 @@ comment "I2C system bus drivers (mostly embedded / system-on-chip)"
 
 config I2C_AT91
 	tristate "Atmel AT91 I2C Two-Wire interface (TWI)"
-	depends on ARCH_AT91 && EXPERIMENTAL && BROKEN
+	depends on ARCH_AT91 && EXPERIMENTAL
 	help
 	  This supports the use of the I2C interface on Atmel AT91
 	  processors.
 
-	  This driver is BROKEN because the controller which it uses
-	  will easily trigger RX overrun and TX underrun errors.  Using
-	  low I2C clock rates may partially work around those issues
-	  on some systems.  Another serious problem is that there is no
-	  documented way to issue repeated START conditions, as needed
+	  A serious problem is that there is no documented way to issue
+	  repeated START conditions for more than two messages, as needed
 	  to support combined I2C messages.  Use the i2c-gpio driver
-	  unless your system can cope with those limitations.
+	  unless your system can cope with this limitation.
 
 config I2C_AU1550
 	tristate "Au1550/Au1200/Au1300 SMBus interface"
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 4f46873..ce3c2be 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_I2C_HYDRA)		+= i2c-hydra.o
 obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 
 # Embedded system I2C/SMBus host controller drivers
+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_CPM)		+= i2c-cpm.o
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
new file mode 100644
index 0000000..2b8b2c2
--- /dev/null
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -0,0 +1,493 @@
+/*
+ *  i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2011 Weinmann Medical GmbH
+ *  Author: Nikolaus Voss <n.voss-+umVssTZoCsb1SvskN2V4Q@public.gmane.org>
+ *
+ *  Evolved from original work by:
+ *  Copyright (C) 2004 Rick Bronson
+ *  Converted to 2.6 by Andrew Victor <andrew-eS41wJS13H5l57MIdRCFDg@public.gmane.org>
+ *
+ *  Borrowed heavily from original work by:
+ *  Copyright (C) 2000 Philip Edelbrock <phil-LT64U7CwzWEZMC/lefXSXFaTQe2KTcn/@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 as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define TWI_CLK_HZ		100000			/* max 400 Kbits/s */
+#define AT91_I2C_TIMEOUT	msecs_to_jiffies(100)	/* transfer timeout */
+
+/* AT91 TWI register definitions */
+#define	AT91_TWI_CR		0x0000	/* Control Register */
+#define	AT91_TWI_START		0x0001	/* Send a Start Condition */
+#define	AT91_TWI_STOP		0x0002	/* Send a Stop Condition */
+#define	AT91_TWI_MSEN		0x0004	/* Master Transfer Enable */
+#define	AT91_TWI_SVDIS		0x0020	/* Slave Transfer Disable */
+#define	AT91_TWI_SWRST		0x0080	/* Software Reset */
+
+#define	AT91_TWI_MMR		0x0004	/* Master Mode Register */
+#define	AT91_TWI_IADRSZ_1	0x0100	/* Internal Device Address Size */
+#define	AT91_TWI_MREAD		0x1000	/* Master Read Direction */
+
+#define	AT91_TWI_IADR		0x000c	/* Internal Address Register */
+
+#define	AT91_TWI_CWGR		0x0010	/* Clock Waveform Generator Reg */
+
+#define	AT91_TWI_SR		0x0020	/* Status Register */
+#define	AT91_TWI_TXCOMP		0x0001	/* Transmission Complete */
+#define	AT91_TWI_RXRDY		0x0002	/* Receive Holding Register Ready */
+#define	AT91_TWI_TXRDY		0x0004	/* Transmit Holding Register Ready */
+
+#define	AT91_TWI_OVRE		0x0040	/* Overrun Error */
+#define	AT91_TWI_UNRE		0x0080	/* Underrun Error */
+#define	AT91_TWI_NACK		0x0100	/* Not Acknowledged */
+
+#define	AT91_TWI_IER		0x0024	/* Interrupt Enable Register */
+#define	AT91_TWI_IDR		0x0028	/* Interrupt Disable Register */
+#define	AT91_TWI_IMR		0x002c	/* Interrupt Mask Register */
+#define	AT91_TWI_RHR		0x0030	/* Receive Holding Register */
+#define	AT91_TWI_THR		0x0034	/* Transmit Holding Register */
+
+enum twi_ip_id {
+	DEFAULT		= 0, /* default ip, no known limitations */
+	RM9200		= 1,
+	SAM9261		= 2,
+};
+
+struct at91_twi_dev {
+	struct device		*dev;
+	void __iomem		*base;
+	struct completion	cmd_complete;
+	struct clk		*clk;
+	u8			*buf;
+	size_t			buf_len;
+	struct i2c_msg		*msg;
+	int			irq;
+	unsigned		transfer_status;
+	struct i2c_adapter	adapter;
+	enum twi_ip_id		ip_id;
+	unsigned		twi_cwgr_reg;
+};
+
+static unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg)
+{
+	return readl_relaxed(dev->base + reg);
+}
+
+static void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val)
+{
+	writel_relaxed(val, dev->base + reg);
+}
+
+static void at91_disable_twi_interrupts(struct at91_twi_dev *dev)
+{
+	at91_twi_write(dev, AT91_TWI_IDR,
+		       AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY);
+}
+
+static void at91_init_twi_bus(struct at91_twi_dev *dev)
+{
+	at91_disable_twi_interrupts(dev);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS);
+	at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg);
+}
+
+/*
+ * Calculate symmetric clock as stated in datasheet:
+ * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset))
+ */
+static void __devinit at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk)
+{
+	int ckdiv, cdiv, div;
+	int offset = 4;
+	int max_ckdiv = 7;
+
+	if (dev->ip_id == RM9200) {
+		offset = 3;
+		max_ckdiv = 5;
+	} else if (dev->ip_id == SAM9261) {
+		offset = 4;
+		max_ckdiv = 5;
+	}
+
+	div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk),
+				       2 * twi_clk) - offset);
+	ckdiv = fls(div >> 8);
+	cdiv = div >> ckdiv;
+
+	if (ckdiv > max_ckdiv) {
+		dev_warn(dev->dev, "%d exceeds ckdiv max value which is %d.\n",
+			 ckdiv, max_ckdiv);
+		ckdiv = max_ckdiv;
+		cdiv = 255;
+	}
+
+	dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv;
+	dev_dbg(dev->dev, "cdiv %d ckdiv %d\n", cdiv, ckdiv);
+}
+
+static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
+{
+	if (dev->buf_len <= 0)
+		return;
+
+	at91_twi_write(dev, AT91_TWI_THR, *dev->buf);
+
+	/* send stop when last byte has been written */
+	if (--dev->buf_len == 0)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+
+	dev_dbg(dev->dev, "wrote 0x%x, to go %d\n", *dev->buf, dev->buf_len);
+
+	++dev->buf;
+}
+
+static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
+{
+	if (dev->buf_len <= 0)
+		return;
+
+	*dev->buf = at91_twi_read(dev, AT91_TWI_RHR) & 0xff;
+	--dev->buf_len;
+
+	/* handle I2C_SMBUS_BLOCK_DATA */
+	if (unlikely(dev->msg->flags & I2C_M_RECV_LEN)) {
+		dev->msg->flags &= ~I2C_M_RECV_LEN;
+		dev->buf_len += *dev->buf;
+		dev->msg->len = dev->buf_len + 1;
+		dev_dbg(dev->dev, "received block length %d\n", dev->buf_len);
+	}
+
+	/* send stop if second but last byte has been read */
+	if (dev->buf_len == 1)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+
+	dev_dbg(dev->dev, "read 0x%x, to go %d\n", *dev->buf, dev->buf_len);
+
+	++dev->buf;
+}
+
+static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id)
+{
+	struct at91_twi_dev *dev = dev_id;
+	const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
+	const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
+
+	if (!irqstatus)
+		return IRQ_NONE;
+	else if (irqstatus & AT91_TWI_RXRDY)
+		at91_twi_read_next_byte(dev);
+	else if (irqstatus & AT91_TWI_TXRDY)
+		at91_twi_write_next_byte(dev);
+
+	/* catch error flags */
+	dev->transfer_status |= status;
+
+	if (irqstatus & AT91_TWI_TXCOMP) {
+		at91_disable_twi_interrupts(dev);
+		complete(&dev->cmd_complete);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int at91_do_twi_transfer(struct at91_twi_dev *dev)
+{
+	int ret;
+
+	dev_dbg(dev->dev, "transfer: %s %d bytes.\n",
+		(dev->msg->flags & I2C_M_RD) ? "read" : "write", dev->buf_len);
+
+	INIT_COMPLETION(dev->cmd_complete);
+	dev->transfer_status = 0;
+	if (dev->msg->flags & I2C_M_RD) {
+		unsigned start_flags = AT91_TWI_START;
+
+		if (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY) {
+			dev_err(dev->dev, "RXRDY still set!");
+			at91_twi_read(dev, AT91_TWI_RHR);
+		}
+
+		/* if only one byte is to be read, immediately stop transfer */
+		if (dev->buf_len <= 1 && !(dev->msg->flags & I2C_M_RECV_LEN))
+			start_flags |= AT91_TWI_STOP;
+		at91_twi_write(dev, AT91_TWI_CR, start_flags);
+		at91_twi_write(dev, AT91_TWI_IER,
+			       AT91_TWI_TXCOMP | AT91_TWI_RXRDY);
+	} else {
+		at91_twi_write_next_byte(dev);
+		at91_twi_write(dev, AT91_TWI_IER,
+			       AT91_TWI_TXCOMP | AT91_TWI_TXRDY);
+	}
+
+	ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
+							dev->adapter.timeout);
+	if (ret == 0) {
+		dev_err(dev->dev, "controller timed out\n");
+		at91_init_twi_bus(dev);
+		return -ETIMEDOUT;
+	}
+	if (dev->transfer_status & AT91_TWI_NACK) {
+		dev_dbg(dev->dev, "received nack\n");
+		return -EREMOTEIO;
+	}
+	if (dev->transfer_status & AT91_TWI_OVRE) {
+		dev_err(dev->dev, "overrun while reading\n");
+		return -EIO;
+	}
+	if (dev->transfer_status & AT91_TWI_UNRE && dev->ip_id == RM9200) {
+		dev_err(dev->dev, "underrun while writing\n");
+		return -EIO;
+	}
+	dev_dbg(dev->dev, "transfer complete\n");
+
+	return 0;
+}
+
+static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(adap);
+	int ret;
+	unsigned int_addr_flag = 0;
+	struct i2c_msg *m_start = msg;
+
+	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
+
+	/*
+	 * The hardware can handle at most two messages concatenated by a
+	 * repeated start via it's internal address feature.
+	 */
+	if (num > 2) {
+		dev_err(dev->dev,
+			"cannot handle more than two concatenated messages.\n");
+		return 0;
+	} else if (num == 2) {
+		int internal_address = 0;
+		int i;
+
+		if (msg->flags & I2C_M_RD) {
+			dev_err(dev->dev, "first transfer must be write.\n");
+			return -EINVAL;
+		}
+		if (msg->len > 3) {
+			dev_err(dev->dev, "first message size must be <= 3.\n");
+			return -EINVAL;
+		}
+
+		/* 1st msg is put into the internal address, start with 2nd */
+		m_start = &msg[1];
+		for (i = 0; i < msg->len; ++i) {
+			const unsigned addr = msg->buf[msg->len - 1 - i];
+
+			internal_address |= addr << (8 * i);
+			int_addr_flag += AT91_TWI_IADRSZ_1;
+		}
+		at91_twi_write(dev, AT91_TWI_IADR, internal_address);
+	}
+
+	at91_twi_write(dev, AT91_TWI_MMR, (m_start->addr << 16) | int_addr_flag
+		       | ((m_start->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0));
+
+	dev->buf_len = m_start->len;
+	dev->buf = m_start->buf;
+	dev->msg = m_start;
+
+	ret = at91_do_twi_transfer(dev);
+
+	return (ret < 0) ? ret : num;
+}
+
+static u32 at91_twi_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
+		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
+}
+
+static struct i2c_algorithm at91_twi_algorithm = {
+	.master_xfer	= at91_twi_xfer,
+	.functionality	= at91_twi_func,
+};
+
+static int __devinit at91_twi_probe(struct platform_device *pdev)
+{
+	struct at91_twi_dev *dev;
+	struct resource *mem, *ioarea;
+	int irq, rc;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem)
+		return -ENODEV;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ioarea = request_mem_region(mem->start, resource_size(mem), pdev->name);
+	if (!ioarea)
+		return -EBUSY;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev) {
+		rc = -ENOMEM;
+		goto err_release_region;
+	}
+
+	if (pdev->id_entry)
+		dev->ip_id = pdev->id_entry->driver_data;
+
+	init_completion(&dev->cmd_complete);
+
+	dev->dev = &pdev->dev;
+	dev->irq = irq;
+	platform_set_drvdata(pdev, dev);
+
+	dev->clk = clk_get(dev->dev, NULL);
+	if (IS_ERR(dev->clk)) {
+		dev_err(dev->dev, "no clock defined\n");
+		rc = -ENODEV;
+		goto err_free_mem;
+	}
+	clk_prepare(dev->clk);
+	clk_enable(dev->clk);
+
+	dev->base = ioremap(mem->start, resource_size(mem));
+	if (!dev->base) {
+		rc = -EBUSY;
+		goto err_mem_ioremap;
+	}
+
+	at91_calc_twi_clock(dev, TWI_CLK_HZ);
+	at91_init_twi_bus(dev);
+
+	rc = request_irq(dev->irq, atmel_twi_interrupt, 0,
+			 dev_name(dev->dev), dev);
+	if (rc) {
+		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
+		goto err_unuse_clocks;
+	}
+
+	snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");
+	i2c_set_adapdata(&dev->adapter, dev);
+	dev->adapter.owner = THIS_MODULE;
+	dev->adapter.class = I2C_CLASS_HWMON;
+	dev->adapter.algo = &at91_twi_algorithm;
+	dev->adapter.dev.parent = dev->dev;
+	dev->adapter.nr = pdev->id;
+	dev->adapter.timeout = AT91_I2C_TIMEOUT;
+
+	rc = i2c_add_numbered_adapter(&dev->adapter);
+	if (rc) {
+		dev_err(dev->dev, "Adapter %s registration failed\n",
+			dev->adapter.name);
+		goto err_free_irq;
+	}
+
+	dev_info(dev->dev, "AT91 i2c bus driver.\n");
+	return 0;
+
+err_free_irq:
+	free_irq(dev->irq, dev);
+err_unuse_clocks:
+	iounmap(dev->base);
+err_mem_ioremap:
+	clk_disable(dev->clk);
+	clk_unprepare(dev->clk);
+	clk_put(dev->clk);
+err_free_mem:
+	kfree(dev);
+err_release_region:
+	release_mem_region(mem->start, resource_size(mem));
+
+	return rc;
+}
+
+static int __devexit at91_twi_remove(struct platform_device *pdev)
+{
+	struct at91_twi_dev *dev = platform_get_drvdata(pdev);
+	struct resource *mem;
+	int rc;
+
+	rc = i2c_del_adapter(&dev->adapter);
+	clk_disable(dev->clk);
+	clk_unprepare(dev->clk);
+	clk_put(dev->clk);
+	free_irq(dev->irq, dev);
+	iounmap(dev->base);
+	kfree(dev);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(mem->start, resource_size(mem));
+
+	return rc;
+}
+
+#ifdef CONFIG_PM
+
+static int at91_twi_runtime_suspend(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+
+	clk_disable(twi_dev->clk);
+
+	return 0;
+}
+
+static int at91_twi_runtime_resume(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+
+	return clk_enable(twi_dev->clk);
+}
+
+static const struct dev_pm_ops at91_twi_pm = {
+	.runtime_suspend	= at91_twi_runtime_suspend,
+	.runtime_resume		= at91_twi_runtime_resume,
+};
+
+#define at91_twi_pm_ops (&at91_twi_pm)
+#else
+#define at91_twi_pm_ops NULL
+#endif
+
+static struct platform_driver at91_twi_driver = {
+	.probe		= at91_twi_probe,
+	.remove		= __devexit_p(at91_twi_remove),
+	.driver		= {
+		.name	= "at91_i2c",
+		.owner	= THIS_MODULE,
+		.pm	= at91_twi_pm_ops,
+	},
+};
+
+static int __init at91_twi_init(void)
+{
+	return platform_driver_register(&at91_twi_driver);
+}
+
+static void __exit at91_twi_exit(void)
+{
+	platform_driver_unregister(&at91_twi_driver);
+}
+
+subsys_initcall(at91_twi_init);
+module_exit(at91_twi_exit);
+
+MODULE_AUTHOR("Nikolaus Voss <n.voss-+umVssTZoCsb1SvskN2V4Q@public.gmane.org>");
+MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:at91_i2c");
-- 
1.7.9.5

[PATCH v11 3/4] drivers/i2c/busses/i2c-at91.c: add new driver

[Nikolaus Voss]

This driver has the following properties compared to the old driver:
1. Support for multiple interfaces.
2. Interrupt driven I/O as opposed to polling/busy waiting.
3. Support for _one_ repeated start (Sr) condition, which is enough
   for most real-world applications including all SMBus transfer types.
   (The hardware does not support issuing arbitrary Sr conditions on the
    bus.)

testing: SoC: at91sam9g45
	 - BQ20Z80 battery SMBus client.
	 - on a 2.6.38 kernel with several i2c clients (temp-sensor,
	   audio-codec, touchscreen-controller, w1-bridge, io-expanders)

Signed-off-by: Nikolaus Voss <n.voss@weinmann.de>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Tested-by: Hubert Feurstein <h.feurstein@gmail.com>

v12: - corrected wrong id_entry on sam9261 twi gpio pdev
v11: - fix for flags persistency suggested by Carsten Behling
     - calc_twi_clock fix for sam9261 by Ludovic Desroches
v10: - applied fix for RXRDY overrun bug submitted by Hubert Feurstein
     - applied fix for calculating twi_clk
v9: - merge i2c-at91.c patches to single patch
    - rewrite cwgr reg after timeout
v8: - remove local include
    - remove cpu_is_rm9200() and put twi hw bug info in platform_device
    - use readl/writel_relaxed instead of __raw_readl/writel
v7: i)  fix bug if internal address > 1 byte
    ii) send stop when len == 1 (both reported by Carsten Behling)
v6: support for I2C_SMBUS_BLOCK_DATA transfers.
    Better use of clk_(un)prepare().
    More sensible transfer timeout.
v5: Another round of review comments from Ryan Mallon, Felipe Balbi
    and Russell King: convert twi clk to use .dev_id, cleanups
v4: Integrated more review comments from Ryan Mallon and Felipe Balbi:
    Moved register include file to local include, code cleanups
v3: Integrated review comments from Ryan Mallon and Felipe Balbi
v2: Fixed whitespace issue
---
 arch/arm/mach-at91/at91rm9200_devices.c  |    9 +
 arch/arm/mach-at91/at91sam9261_devices.c |    9 +
 drivers/i2c/busses/Kconfig               |   11 +-
 drivers/i2c/busses/Makefile              |    1 +
 drivers/i2c/busses/i2c-at91.c            |  493 ++++++++++++++++++++++++++++++
 5 files changed, 516 insertions(+), 7 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-at91.c

diff --git a/arch/arm/mach-at91/at91rm9200_devices.c b/arch/arm/mach-at91/at91rm9200_devices.c
index e6b7d05..2977a2d 100644
--- a/arch/arm/mach-at91/at91rm9200_devices.c
+++ b/arch/arm/mach-at91/at91rm9200_devices.c
@@ -494,9 +494,18 @@ static struct resource twi_resources[] = {
 	},
 };
 
+static const struct platform_device_id twi_ip_type = {
+	/*
+	 * driver_data is 1 for RM9200 compatible ip, see enum twi_ip_id in
+	 * drivers/i2c/busses/i2c-at91.c
+	 */
+	.driver_data	= 1,
+};
+
 static struct platform_device at91rm9200_twi_device = {
 	.name		= "at91_i2c",
 	.id		= -1,
+	.id_entry	= &twi_ip_type,
 	.resource	= twi_resources,
 	.num_resources	= ARRAY_SIZE(twi_resources),
 };
diff --git a/arch/arm/mach-at91/at91sam9261_devices.c b/arch/arm/mach-at91/at91sam9261_devices.c
index 9295e90..aeb2eed 100644
--- a/arch/arm/mach-at91/at91sam9261_devices.c
+++ b/arch/arm/mach-at91/at91sam9261_devices.c
@@ -316,9 +316,18 @@ static struct resource twi_resources[] = {
 	},
 };
 
+static const struct platform_device_id twi_ip_type = {
+	/*
+	 * driver_data is 2 for SAM9261 compatible ip, see enum twi_ip_id in
+	 * drivers/i2c/busses/i2c-at91.c
+	 */
+	.driver_data	= 2,
+};
+
 static struct platform_device at91sam9261_twi_device = {
 	.name		= "at91_i2c",
 	.id		= -1,
+	.id_entry	= &twi_ip_type,
 	.resource	= twi_resources,
 	.num_resources	= ARRAY_SIZE(twi_resources),
 };
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 7244c8b..6b74287 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -286,18 +286,15 @@ comment "I2C system bus drivers (mostly embedded / system-on-chip)"
 
 config I2C_AT91
 	tristate "Atmel AT91 I2C Two-Wire interface (TWI)"
-	depends on ARCH_AT91 && EXPERIMENTAL && BROKEN
+	depends on ARCH_AT91 && EXPERIMENTAL
 	help
 	  This supports the use of the I2C interface on Atmel AT91
 	  processors.
 
-	  This driver is BROKEN because the controller which it uses
-	  will easily trigger RX overrun and TX underrun errors.  Using
-	  low I2C clock rates may partially work around those issues
-	  on some systems.  Another serious problem is that there is no
-	  documented way to issue repeated START conditions, as needed
+	  A serious problem is that there is no documented way to issue
+	  repeated START conditions for more than two messages, as needed
 	  to support combined I2C messages.  Use the i2c-gpio driver
-	  unless your system can cope with those limitations.
+	  unless your system can cope with this limitation.
 
 config I2C_AU1550
 	tristate "Au1550/Au1200/Au1300 SMBus interface"
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 4f46873..ce3c2be 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_I2C_HYDRA)		+= i2c-hydra.o
 obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 
 # Embedded system I2C/SMBus host controller drivers
+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_CPM)		+= i2c-cpm.o
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
new file mode 100644
index 0000000..2b8b2c2
--- /dev/null
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -0,0 +1,493 @@
+/*
+ *  i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2011 Weinmann Medical GmbH
+ *  Author: Nikolaus Voss <n.voss@weinmann.de>
+ *
+ *  Evolved from original work by:
+ *  Copyright (C) 2004 Rick Bronson
+ *  Converted to 2.6 by Andrew Victor <andrew@sanpeople.com>
+ *
+ *  Borrowed heavily from original work by:
+ *  Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define TWI_CLK_HZ		100000			/* max 400 Kbits/s */
+#define AT91_I2C_TIMEOUT	msecs_to_jiffies(100)	/* transfer timeout */
+
+/* AT91 TWI register definitions */
+#define	AT91_TWI_CR		0x0000	/* Control Register */
+#define	AT91_TWI_START		0x0001	/* Send a Start Condition */
+#define	AT91_TWI_STOP		0x0002	/* Send a Stop Condition */
+#define	AT91_TWI_MSEN		0x0004	/* Master Transfer Enable */
+#define	AT91_TWI_SVDIS		0x0020	/* Slave Transfer Disable */
+#define	AT91_TWI_SWRST		0x0080	/* Software Reset */
+
+#define	AT91_TWI_MMR		0x0004	/* Master Mode Register */
+#define	AT91_TWI_IADRSZ_1	0x0100	/* Internal Device Address Size */
+#define	AT91_TWI_MREAD		0x1000	/* Master Read Direction */
+
+#define	AT91_TWI_IADR		0x000c	/* Internal Address Register */
+
+#define	AT91_TWI_CWGR		0x0010	/* Clock Waveform Generator Reg */
+
+#define	AT91_TWI_SR		0x0020	/* Status Register */
+#define	AT91_TWI_TXCOMP		0x0001	/* Transmission Complete */
+#define	AT91_TWI_RXRDY		0x0002	/* Receive Holding Register Ready */
+#define	AT91_TWI_TXRDY		0x0004	/* Transmit Holding Register Ready */
+
+#define	AT91_TWI_OVRE		0x0040	/* Overrun Error */
+#define	AT91_TWI_UNRE		0x0080	/* Underrun Error */
+#define	AT91_TWI_NACK		0x0100	/* Not Acknowledged */
+
+#define	AT91_TWI_IER		0x0024	/* Interrupt Enable Register */
+#define	AT91_TWI_IDR		0x0028	/* Interrupt Disable Register */
+#define	AT91_TWI_IMR		0x002c	/* Interrupt Mask Register */
+#define	AT91_TWI_RHR		0x0030	/* Receive Holding Register */
+#define	AT91_TWI_THR		0x0034	/* Transmit Holding Register */
+
+enum twi_ip_id {
+	DEFAULT		= 0, /* default ip, no known limitations */
+	RM9200		= 1,
+	SAM9261		= 2,
+};
+
+struct at91_twi_dev {
+	struct device		*dev;
+	void __iomem		*base;
+	struct completion	cmd_complete;
+	struct clk		*clk;
+	u8			*buf;
+	size_t			buf_len;
+	struct i2c_msg		*msg;
+	int			irq;
+	unsigned		transfer_status;
+	struct i2c_adapter	adapter;
+	enum twi_ip_id		ip_id;
+	unsigned		twi_cwgr_reg;
+};
+
+static unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg)
+{
+	return readl_relaxed(dev->base + reg);
+}
+
+static void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val)
+{
+	writel_relaxed(val, dev->base + reg);
+}
+
+static void at91_disable_twi_interrupts(struct at91_twi_dev *dev)
+{
+	at91_twi_write(dev, AT91_TWI_IDR,
+		       AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY);
+}
+
+static void at91_init_twi_bus(struct at91_twi_dev *dev)
+{
+	at91_disable_twi_interrupts(dev);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS);
+	at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg);
+}
+
+/*
+ * Calculate symmetric clock as stated in datasheet:
+ * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset))
+ */
+static void __devinit at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk)
+{
+	int ckdiv, cdiv, div;
+	int offset = 4;
+	int max_ckdiv = 7;
+
+	if (dev->ip_id == RM9200) {
+		offset = 3;
+		max_ckdiv = 5;
+	} else if (dev->ip_id == SAM9261) {
+		offset = 4;
+		max_ckdiv = 5;
+	}
+
+	div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk),
+				       2 * twi_clk) - offset);
+	ckdiv = fls(div >> 8);
+	cdiv = div >> ckdiv;
+
+	if (ckdiv > max_ckdiv) {
+		dev_warn(dev->dev, "%d exceeds ckdiv max value which is %d.\n",
+			 ckdiv, max_ckdiv);
+		ckdiv = max_ckdiv;
+		cdiv = 255;
+	}
+
+	dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv;
+	dev_dbg(dev->dev, "cdiv %d ckdiv %d\n", cdiv, ckdiv);
+}
+
+static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
+{
+	if (dev->buf_len <= 0)
+		return;
+
+	at91_twi_write(dev, AT91_TWI_THR, *dev->buf);
+
+	/* send stop when last byte has been written */
+	if (--dev->buf_len == 0)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+
+	dev_dbg(dev->dev, "wrote 0x%x, to go %d\n", *dev->buf, dev->buf_len);
+
+	++dev->buf;
+}
+
+static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
+{
+	if (dev->buf_len <= 0)
+		return;
+
+	*dev->buf = at91_twi_read(dev, AT91_TWI_RHR) & 0xff;
+	--dev->buf_len;
+
+	/* handle I2C_SMBUS_BLOCK_DATA */
+	if (unlikely(dev->msg->flags & I2C_M_RECV_LEN)) {
+		dev->msg->flags &= ~I2C_M_RECV_LEN;
+		dev->buf_len += *dev->buf;
+		dev->msg->len = dev->buf_len + 1;
+		dev_dbg(dev->dev, "received block length %d\n", dev->buf_len);
+	}
+
+	/* send stop if second but last byte has been read */
+	if (dev->buf_len == 1)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+
+	dev_dbg(dev->dev, "read 0x%x, to go %d\n", *dev->buf, dev->buf_len);
+
+	++dev->buf;
+}
+
+static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id)
+{
+	struct at91_twi_dev *dev = dev_id;
+	const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
+	const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
+
+	if (!irqstatus)
+		return IRQ_NONE;
+	else if (irqstatus & AT91_TWI_RXRDY)
+		at91_twi_read_next_byte(dev);
+	else if (irqstatus & AT91_TWI_TXRDY)
+		at91_twi_write_next_byte(dev);
+
+	/* catch error flags */
+	dev->transfer_status |= status;
+
+	if (irqstatus & AT91_TWI_TXCOMP) {
+		at91_disable_twi_interrupts(dev);
+		complete(&dev->cmd_complete);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int at91_do_twi_transfer(struct at91_twi_dev *dev)
+{
+	int ret;
+
+	dev_dbg(dev->dev, "transfer: %s %d bytes.\n",
+		(dev->msg->flags & I2C_M_RD) ? "read" : "write", dev->buf_len);
+
+	INIT_COMPLETION(dev->cmd_complete);
+	dev->transfer_status = 0;
+	if (dev->msg->flags & I2C_M_RD) {
+		unsigned start_flags = AT91_TWI_START;
+
+		if (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY) {
+			dev_err(dev->dev, "RXRDY still set!");
+			at91_twi_read(dev, AT91_TWI_RHR);
+		}
+
+		/* if only one byte is to be read, immediately stop transfer */
+		if (dev->buf_len <= 1 && !(dev->msg->flags & I2C_M_RECV_LEN))
+			start_flags |= AT91_TWI_STOP;
+		at91_twi_write(dev, AT91_TWI_CR, start_flags);
+		at91_twi_write(dev, AT91_TWI_IER,
+			       AT91_TWI_TXCOMP | AT91_TWI_RXRDY);
+	} else {
+		at91_twi_write_next_byte(dev);
+		at91_twi_write(dev, AT91_TWI_IER,
+			       AT91_TWI_TXCOMP | AT91_TWI_TXRDY);
+	}
+
+	ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
+							dev->adapter.timeout);
+	if (ret == 0) {
+		dev_err(dev->dev, "controller timed out\n");
+		at91_init_twi_bus(dev);
+		return -ETIMEDOUT;
+	}
+	if (dev->transfer_status & AT91_TWI_NACK) {
+		dev_dbg(dev->dev, "received nack\n");
+		return -EREMOTEIO;
+	}
+	if (dev->transfer_status & AT91_TWI_OVRE) {
+		dev_err(dev->dev, "overrun while reading\n");
+		return -EIO;
+	}
+	if (dev->transfer_status & AT91_TWI_UNRE && dev->ip_id == RM9200) {
+		dev_err(dev->dev, "underrun while writing\n");
+		return -EIO;
+	}
+	dev_dbg(dev->dev, "transfer complete\n");
+
+	return 0;
+}
+
+static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(adap);
+	int ret;
+	unsigned int_addr_flag = 0;
+	struct i2c_msg *m_start = msg;
+
+	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
+
+	/*
+	 * The hardware can handle at most two messages concatenated by a
+	 * repeated start via it's internal address feature.
+	 */
+	if (num > 2) {
+		dev_err(dev->dev,
+			"cannot handle more than two concatenated messages.\n");
+		return 0;
+	} else if (num == 2) {
+		int internal_address = 0;
+		int i;
+
+		if (msg->flags & I2C_M_RD) {
+			dev_err(dev->dev, "first transfer must be write.\n");
+			return -EINVAL;
+		}
+		if (msg->len > 3) {
+			dev_err(dev->dev, "first message size must be <= 3.\n");
+			return -EINVAL;
+		}
+
+		/* 1st msg is put into the internal address, start with 2nd */
+		m_start = &msg[1];
+		for (i = 0; i < msg->len; ++i) {
+			const unsigned addr = msg->buf[msg->len - 1 - i];
+
+			internal_address |= addr << (8 * i);
+			int_addr_flag += AT91_TWI_IADRSZ_1;
+		}
+		at91_twi_write(dev, AT91_TWI_IADR, internal_address);
+	}
+
+	at91_twi_write(dev, AT91_TWI_MMR, (m_start->addr << 16) | int_addr_flag
+		       | ((m_start->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0));
+
+	dev->buf_len = m_start->len;
+	dev->buf = m_start->buf;
+	dev->msg = m_start;
+
+	ret = at91_do_twi_transfer(dev);
+
+	return (ret < 0) ? ret : num;
+}
+
+static u32 at91_twi_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
+		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
+}
+
+static struct i2c_algorithm at91_twi_algorithm = {
+	.master_xfer	= at91_twi_xfer,
+	.functionality	= at91_twi_func,
+};
+
+static int __devinit at91_twi_probe(struct platform_device *pdev)
+{
+	struct at91_twi_dev *dev;
+	struct resource *mem, *ioarea;
+	int irq, rc;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem)
+		return -ENODEV;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ioarea = request_mem_region(mem->start, resource_size(mem), pdev->name);
+	if (!ioarea)
+		return -EBUSY;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev) {
+		rc = -ENOMEM;
+		goto err_release_region;
+	}
+
+	if (pdev->id_entry)
+		dev->ip_id = pdev->id_entry->driver_data;
+
+	init_completion(&dev->cmd_complete);
+
+	dev->dev = &pdev->dev;
+	dev->irq = irq;
+	platform_set_drvdata(pdev, dev);
+
+	dev->clk = clk_get(dev->dev, NULL);
+	if (IS_ERR(dev->clk)) {
+		dev_err(dev->dev, "no clock defined\n");
+		rc = -ENODEV;
+		goto err_free_mem;
+	}
+	clk_prepare(dev->clk);
+	clk_enable(dev->clk);
+
+	dev->base = ioremap(mem->start, resource_size(mem));
+	if (!dev->base) {
+		rc = -EBUSY;
+		goto err_mem_ioremap;
+	}
+
+	at91_calc_twi_clock(dev, TWI_CLK_HZ);
+	at91_init_twi_bus(dev);
+
+	rc = request_irq(dev->irq, atmel_twi_interrupt, 0,
+			 dev_name(dev->dev), dev);
+	if (rc) {
+		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
+		goto err_unuse_clocks;
+	}
+
+	snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");
+	i2c_set_adapdata(&dev->adapter, dev);
+	dev->adapter.owner = THIS_MODULE;
+	dev->adapter.class = I2C_CLASS_HWMON;
+	dev->adapter.algo = &at91_twi_algorithm;
+	dev->adapter.dev.parent = dev->dev;
+	dev->adapter.nr = pdev->id;
+	dev->adapter.timeout = AT91_I2C_TIMEOUT;
+
+	rc = i2c_add_numbered_adapter(&dev->adapter);
+	if (rc) {
+		dev_err(dev->dev, "Adapter %s registration failed\n",
+			dev->adapter.name);
+		goto err_free_irq;
+	}
+
+	dev_info(dev->dev, "AT91 i2c bus driver.\n");
+	return 0;
+
+err_free_irq:
+	free_irq(dev->irq, dev);
+err_unuse_clocks:
+	iounmap(dev->base);
+err_mem_ioremap:
+	clk_disable(dev->clk);
+	clk_unprepare(dev->clk);
+	clk_put(dev->clk);
+err_free_mem:
+	kfree(dev);
+err_release_region:
+	release_mem_region(mem->start, resource_size(mem));
+
+	return rc;
+}
+
+static int __devexit at91_twi_remove(struct platform_device *pdev)
+{
+	struct at91_twi_dev *dev = platform_get_drvdata(pdev);
+	struct resource *mem;
+	int rc;
+
+	rc = i2c_del_adapter(&dev->adapter);
+	clk_disable(dev->clk);
+	clk_unprepare(dev->clk);
+	clk_put(dev->clk);
+	free_irq(dev->irq, dev);
+	iounmap(dev->base);
+	kfree(dev);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(mem->start, resource_size(mem));
+
+	return rc;
+}
+
+#ifdef CONFIG_PM
+
+static int at91_twi_runtime_suspend(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+
+	clk_disable(twi_dev->clk);
+
+	return 0;
+}
+
+static int at91_twi_runtime_resume(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+
+	return clk_enable(twi_dev->clk);
+}
+
+static const struct dev_pm_ops at91_twi_pm = {
+	.runtime_suspend	= at91_twi_runtime_suspend,
+	.runtime_resume		= at91_twi_runtime_resume,
+};
+
+#define at91_twi_pm_ops (&at91_twi_pm)
+#else
+#define at91_twi_pm_ops NULL
+#endif
+
+static struct platform_driver at91_twi_driver = {
+	.probe		= at91_twi_probe,
+	.remove		= __devexit_p(at91_twi_remove),
+	.driver		= {
+		.name	= "at91_i2c",
+		.owner	= THIS_MODULE,
+		.pm	= at91_twi_pm_ops,
+	},
+};
+
+static int __init at91_twi_init(void)
+{
+	return platform_driver_register(&at91_twi_driver);
+}
+
+static void __exit at91_twi_exit(void)
+{
+	platform_driver_unregister(&at91_twi_driver);
+}
+
+subsys_initcall(at91_twi_init);
+module_exit(at91_twi_exit);
+
+MODULE_AUTHOR("Nikolaus Voss <n.voss@weinmann.de>");
+MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:at91_i2c");
-- 
1.7.9.5

Re: [PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[Nicolas Ferre]

On 08/29/2012 09:28 AM, Nikolaus Voss :
> The old driver has two main deficencies:
> i)  No repeated start (Sr) condiction is possible, this makes it unusable
>     e.g. for most SMBus transfers.
> ii) I/O was done with polling/busy waiting what caused over-/underruns
>     even at light system loads and clock speeds.
> 
> The new driver overcomes these deficencies and in addition allows for
> more than one TWI interface.
> 
> A remaining limitation is the fact, that only one repeated start is
> possible (two concatenated messages). This limitation is imposed by
> the hardware. However, this should not be a problem as all common
> i2c-client communication does not rely on more than one repeated start.
> 
> Changes since v11:
> - corrected wrong id_entry on sam9261 twi gpio pdev

Hi Wolfram,

Despite the patch revision written in the subject, it is actually the
real v12 patch series from Nikolaus.
BTW, I suspect that you were not in copy...

In addition to the "Tested-By" tag by Ludovic, you can add my:

Reviewed-by: Nicolas Ferre <nicolas.ferre-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>


> Nikolaus Voss (4):
>   drivers/i2c/busses/i2c-at91.c: remove old polling driver
>   Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
>   drivers/i2c/busses/i2c-at91.c: add new driver
>   G45 TWI: remove open drain setting for twi function gpios
> 
>  arch/arm/mach-at91/at91rm9200.c            |    1 +
>  arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
>  arch/arm/mach-at91/at91sam9260.c           |    1 +
>  arch/arm/mach-at91/at91sam9261.c           |    1 +
>  arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
>  arch/arm/mach-at91/at91sam9263.c           |    1 +
>  arch/arm/mach-at91/at91sam9g45.c           |    2 +
>  arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
>  arch/arm/mach-at91/at91sam9rl.c            |    2 +
>  arch/arm/mach-at91/at91sam9x5.c            |    3 +
>  arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
>  drivers/i2c/busses/Kconfig                 |   11 +-
>  drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
>  13 files changed, 418 insertions(+), 287 deletions(-)
>  delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
> 


-- 
Nicolas Ferre

Re: [PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[Nicolas Ferre]

On 08/29/2012 09:28 AM, Nikolaus Voss :
> The old driver has two main deficencies:
> i)  No repeated start (Sr) condiction is possible, this makes it unusable
>     e.g. for most SMBus transfers.
> ii) I/O was done with polling/busy waiting what caused over-/underruns
>     even at light system loads and clock speeds.
> 
> The new driver overcomes these deficencies and in addition allows for
> more than one TWI interface.
> 
> A remaining limitation is the fact, that only one repeated start is
> possible (two concatenated messages). This limitation is imposed by
> the hardware. However, this should not be a problem as all common
> i2c-client communication does not rely on more than one repeated start.
> 
> Changes since v11:
> - corrected wrong id_entry on sam9261 twi gpio pdev

Hi Wolfram,

Despite the patch revision written in the subject, it is actually the
real v12 patch series from Nikolaus.
BTW, I suspect that you were not in copy...

In addition to the "Tested-By" tag by Ludovic, you can add my:

Reviewed-by: Nicolas Ferre <nicolas.ferre@atmel.com>


> Nikolaus Voss (4):
>   drivers/i2c/busses/i2c-at91.c: remove old polling driver
>   Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
>   drivers/i2c/busses/i2c-at91.c: add new driver
>   G45 TWI: remove open drain setting for twi function gpios
> 
>  arch/arm/mach-at91/at91rm9200.c            |    1 +
>  arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
>  arch/arm/mach-at91/at91sam9260.c           |    1 +
>  arch/arm/mach-at91/at91sam9261.c           |    1 +
>  arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
>  arch/arm/mach-at91/at91sam9263.c           |    1 +
>  arch/arm/mach-at91/at91sam9g45.c           |    2 +
>  arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
>  arch/arm/mach-at91/at91sam9rl.c            |    2 +
>  arch/arm/mach-at91/at91sam9x5.c            |    3 +
>  arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
>  drivers/i2c/busses/Kconfig                 |   11 +-
>  drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
>  13 files changed, 418 insertions(+), 287 deletions(-)
>  delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
> 


-- 
Nicolas Ferre

[PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[Nicolas Ferre]

On 08/29/2012 09:28 AM, Nikolaus Voss :
> The old driver has two main deficencies:
> i)  No repeated start (Sr) condiction is possible, this makes it unusable
>     e.g. for most SMBus transfers.
> ii) I/O was done with polling/busy waiting what caused over-/underruns
>     even at light system loads and clock speeds.
> 
> The new driver overcomes these deficencies and in addition allows for
> more than one TWI interface.
> 
> A remaining limitation is the fact, that only one repeated start is
> possible (two concatenated messages). This limitation is imposed by
> the hardware. However, this should not be a problem as all common
> i2c-client communication does not rely on more than one repeated start.
> 
> Changes since v11:
> - corrected wrong id_entry on sam9261 twi gpio pdev

Hi Wolfram,

Despite the patch revision written in the subject, it is actually the
real v12 patch series from Nikolaus.
BTW, I suspect that you were not in copy...

In addition to the "Tested-By" tag by Ludovic, you can add my:

Reviewed-by: Nicolas Ferre <nicolas.ferre@atmel.com>


> Nikolaus Voss (4):
>   drivers/i2c/busses/i2c-at91.c: remove old polling driver
>   Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
>   drivers/i2c/busses/i2c-at91.c: add new driver
>   G45 TWI: remove open drain setting for twi function gpios
> 
>  arch/arm/mach-at91/at91rm9200.c            |    1 +
>  arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
>  arch/arm/mach-at91/at91sam9260.c           |    1 +
>  arch/arm/mach-at91/at91sam9261.c           |    1 +
>  arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
>  arch/arm/mach-at91/at91sam9263.c           |    1 +
>  arch/arm/mach-at91/at91sam9g45.c           |    2 +
>  arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
>  arch/arm/mach-at91/at91sam9rl.c            |    2 +
>  arch/arm/mach-at91/at91sam9x5.c            |    3 +
>  arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
>  drivers/i2c/busses/Kconfig                 |   11 +-
>  drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
>  13 files changed, 418 insertions(+), 287 deletions(-)
>  delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
> 


-- 
Nicolas Ferre

[PATCH v11 2/4] Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk

[Nikolaus Voss]

The old driver used con_id clock entries. Convert to use dev_id
for clock lookup via standard method.

Signed-off-by: Nikolaus Voss <n.voss@weinmann.de>
---
 arch/arm/mach-at91/at91rm9200.c  |    1 +
 arch/arm/mach-at91/at91sam9260.c |    1 +
 arch/arm/mach-at91/at91sam9261.c |    1 +
 arch/arm/mach-at91/at91sam9263.c |    1 +
 arch/arm/mach-at91/at91sam9g45.c |    2 ++
 arch/arm/mach-at91/at91sam9rl.c  |    2 ++
 arch/arm/mach-at91/at91sam9x5.c  |    3 +++
 7 files changed, 11 insertions(+)

diff --git a/arch/arm/mach-at91/at91rm9200.c b/arch/arm/mach-at91/at91rm9200.c
index 2691768..cf354a3 100644
--- a/arch/arm/mach-at91/at91rm9200.c
+++ b/arch/arm/mach-at91/at91rm9200.c
@@ -186,6 +186,7 @@ static struct clk_lookup periph_clocks_lookups[] = {
 	CLKDEV_CON_DEV_ID("pclk", "ssc.0", &ssc0_clk),
 	CLKDEV_CON_DEV_ID("pclk", "ssc.1", &ssc1_clk),
 	CLKDEV_CON_DEV_ID("pclk", "ssc.2", &ssc2_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c", &twi_clk),
 	/* fake hclk clock */
 	CLKDEV_CON_DEV_ID("hclk", "at91_ohci", &ohci_clk),
 	CLKDEV_CON_ID("pioA", &pioA_clk),
diff --git a/arch/arm/mach-at91/at91sam9260.c b/arch/arm/mach-at91/at91sam9260.c
index 2b1e438..2e56321 100644
--- a/arch/arm/mach-at91/at91sam9260.c
+++ b/arch/arm/mach-at91/at91sam9260.c
@@ -210,6 +210,7 @@ static struct clk_lookup periph_clocks_lookups[] = {
 	CLKDEV_CON_DEV_ID("t1_clk", "atmel_tcb.1", &tc4_clk),
 	CLKDEV_CON_DEV_ID("t2_clk", "atmel_tcb.1", &tc5_clk),
 	CLKDEV_CON_DEV_ID("pclk", "ssc.0", &ssc_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c", &twi_clk),
 	/* more usart lookup table for DT entries */
 	CLKDEV_CON_DEV_ID("usart", "fffff200.serial", &mck),
 	CLKDEV_CON_DEV_ID("usart", "fffb0000.serial", &usart0_clk),
diff --git a/arch/arm/mach-at91/at91sam9261.c b/arch/arm/mach-at91/at91sam9261.c
index c77d503..f21196d 100644
--- a/arch/arm/mach-at91/at91sam9261.c
+++ b/arch/arm/mach-at91/at91sam9261.c
@@ -177,6 +177,7 @@ static struct clk_lookup periph_clocks_lookups[] = {
 	CLKDEV_CON_DEV_ID("pclk", "ssc.1", &ssc1_clk),
 	CLKDEV_CON_DEV_ID("pclk", "ssc.2", &ssc2_clk),
 	CLKDEV_CON_DEV_ID("hclk", "at91_ohci", &hck0),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c", &twi_clk),
 	CLKDEV_CON_ID("pioA", &pioA_clk),
 	CLKDEV_CON_ID("pioB", &pioB_clk),
 	CLKDEV_CON_ID("pioC", &pioC_clk),
diff --git a/arch/arm/mach-at91/at91sam9263.c b/arch/arm/mach-at91/at91sam9263.c
index ed91c7e..71305fa 100644
--- a/arch/arm/mach-at91/at91sam9263.c
+++ b/arch/arm/mach-at91/at91sam9263.c
@@ -192,6 +192,7 @@ static struct clk_lookup periph_clocks_lookups[] = {
 	CLKDEV_CON_DEV_ID("spi_clk", "atmel_spi.0", &spi0_clk),
 	CLKDEV_CON_DEV_ID("spi_clk", "atmel_spi.1", &spi1_clk),
 	CLKDEV_CON_DEV_ID("t0_clk", "atmel_tcb.0", &tcb_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c", &twi_clk),
 	/* fake hclk clock */
 	CLKDEV_CON_DEV_ID("hclk", "at91_ohci", &ohci_clk),
 	CLKDEV_CON_ID("pioA", &pioA_clk),
diff --git a/arch/arm/mach-at91/at91sam9g45.c b/arch/arm/mach-at91/at91sam9g45.c
index 4792682..2944fc7 100644
--- a/arch/arm/mach-at91/at91sam9g45.c
+++ b/arch/arm/mach-at91/at91sam9g45.c
@@ -228,6 +228,8 @@ static struct clk_lookup periph_clocks_lookups[] = {
 	CLKDEV_CON_DEV_ID("spi_clk", "atmel_spi.1", &spi1_clk),
 	CLKDEV_CON_DEV_ID("t0_clk", "atmel_tcb.0", &tcb0_clk),
 	CLKDEV_CON_DEV_ID("t0_clk", "atmel_tcb.1", &tcb0_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c.0", &twi0_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c.1", &twi1_clk),
 	CLKDEV_CON_DEV_ID("pclk", "ssc.0", &ssc0_clk),
 	CLKDEV_CON_DEV_ID("pclk", "ssc.1", &ssc1_clk),
 	CLKDEV_CON_DEV_ID(NULL, "atmel-trng", &trng_clk),
diff --git a/arch/arm/mach-at91/at91sam9rl.c b/arch/arm/mach-at91/at91sam9rl.c
index e420085..8a97218 100644
--- a/arch/arm/mach-at91/at91sam9rl.c
+++ b/arch/arm/mach-at91/at91sam9rl.c
@@ -185,6 +185,8 @@ static struct clk_lookup periph_clocks_lookups[] = {
 	CLKDEV_CON_DEV_ID("t2_clk", "atmel_tcb.0", &tc2_clk),
 	CLKDEV_CON_DEV_ID("pclk", "ssc.0", &ssc0_clk),
 	CLKDEV_CON_DEV_ID("pclk", "ssc.1", &ssc1_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c.0", &twi0_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c.1", &twi1_clk),
 	CLKDEV_CON_ID("pioA", &pioA_clk),
 	CLKDEV_CON_ID("pioB", &pioB_clk),
 	CLKDEV_CON_ID("pioC", &pioC_clk),
diff --git a/arch/arm/mach-at91/at91sam9x5.c b/arch/arm/mach-at91/at91sam9x5.c
index 1b144b4..def85e5 100644
--- a/arch/arm/mach-at91/at91sam9x5.c
+++ b/arch/arm/mach-at91/at91sam9x5.c
@@ -231,6 +231,9 @@ static struct clk_lookup periph_clocks_lookups[] = {
 	CLKDEV_CON_DEV_ID("t0_clk", "f800c000.timer", &tcb0_clk),
 	CLKDEV_CON_DEV_ID("dma_clk", "ffffec00.dma-controller", &dma0_clk),
 	CLKDEV_CON_DEV_ID("dma_clk", "ffffee00.dma-controller", &dma1_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c.0", &twi0_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c.1", &twi1_clk),
+	CLKDEV_CON_DEV_ID(NULL, "at91_i2c.2", &twi2_clk),
 	CLKDEV_CON_ID("pioA", &pioAB_clk),
 	CLKDEV_CON_ID("pioB", &pioAB_clk),
 	CLKDEV_CON_ID("pioC", &pioCD_clk),
-- 
1.7.9.5

[PATCH v11 4/4] G45 TWI: remove open drain setting for twi function gpios

[Nikolaus Voss]

The G45 datasheets explicitly states that setting the open drain property
on peripheral function gpios is not allowed. (How about other A91 chips?)

Signed-off-by: Nikolaus Voss <n.voss@weinmann.de>
---
 arch/arm/mach-at91/at91sam9g45_devices.c |    6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/arm/mach-at91/at91sam9g45_devices.c b/arch/arm/mach-at91/at91sam9g45_devices.c
index eec5eb6..2134663 100644
--- a/arch/arm/mach-at91/at91sam9g45_devices.c
+++ b/arch/arm/mach-at91/at91sam9g45_devices.c
@@ -686,18 +686,12 @@ void __init at91_add_device_i2c(short i2c_id, struct i2c_board_info *devices, in
 	/* pins used for TWI interface */
 	if (i2c_id == 0) {
 		at91_set_A_periph(AT91_PIN_PA20, 0);		/* TWD */
-		at91_set_multi_drive(AT91_PIN_PA20, 1);
-
 		at91_set_A_periph(AT91_PIN_PA21, 0);		/* TWCK */
-		at91_set_multi_drive(AT91_PIN_PA21, 1);
 
 		platform_device_register(&at91sam9g45_twi0_device);
 	} else {
 		at91_set_A_periph(AT91_PIN_PB10, 0);		/* TWD */
-		at91_set_multi_drive(AT91_PIN_PB10, 1);
-
 		at91_set_A_periph(AT91_PIN_PB11, 0);		/* TWCK */
-		at91_set_multi_drive(AT91_PIN_PB11, 1);
 
 		platform_device_register(&at91sam9g45_twi1_device);
 	}
-- 
1.7.9.5

Re: [PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[ludovic.desroches]

Hi Nikolaus,

Le 08/29/2012 09:28 AM, Nikolaus Voss a écrit :
> The old driver has two main deficencies:
> i)  No repeated start (Sr) condiction is possible, this makes it unusable
>      e.g. for most SMBus transfers.
> ii) I/O was done with polling/busy waiting what caused over-/underruns
>      even at light system loads and clock speeds.
>
> The new driver overcomes these deficencies and in addition allows for
> more than one TWI interface.
>
> A remaining limitation is the fact, that only one repeated start is
> possible (two concatenated messages). This limitation is imposed by
> the hardware. However, this should not be a problem as all common
> i2c-client communication does not rely on more than one repeated start.
>
> Changes since v11:
> - corrected wrong id_entry on sam9261 twi gpio pdev
>

Thanks for this new version, you can add
Tested-By: Ludovic Desroches <ludovic.desroches@atmel.com>
for the whole series.

Concerning the open drain issue, even if I don't have it on my board 
your patch is correct it is needed also for chips. Once I'll have the 
complete list, I'll send an additional patch.

Regards

Ludovic


> Nikolaus Voss (4):
>    drivers/i2c/busses/i2c-at91.c: remove old polling driver
>    Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
>    drivers/i2c/busses/i2c-at91.c: add new driver
>    G45 TWI: remove open drain setting for twi function gpios
>
>   arch/arm/mach-at91/at91rm9200.c            |    1 +
>   arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
>   arch/arm/mach-at91/at91sam9260.c           |    1 +
>   arch/arm/mach-at91/at91sam9261.c           |    1 +
>   arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
>   arch/arm/mach-at91/at91sam9263.c           |    1 +
>   arch/arm/mach-at91/at91sam9g45.c           |    2 +
>   arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
>   arch/arm/mach-at91/at91sam9rl.c            |    2 +
>   arch/arm/mach-at91/at91sam9x5.c            |    3 +
>   arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
>   drivers/i2c/busses/Kconfig                 |   11 +-
>   drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
>   13 files changed, 418 insertions(+), 287 deletions(-)
>   delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
>

[PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[ludovic.desroches]

Hi Nikolaus,

Le 08/29/2012 09:28 AM, Nikolaus Voss a ?crit :
> The old driver has two main deficencies:
> i)  No repeated start (Sr) condiction is possible, this makes it unusable
>      e.g. for most SMBus transfers.
> ii) I/O was done with polling/busy waiting what caused over-/underruns
>      even at light system loads and clock speeds.
>
> The new driver overcomes these deficencies and in addition allows for
> more than one TWI interface.
>
> A remaining limitation is the fact, that only one repeated start is
> possible (two concatenated messages). This limitation is imposed by
> the hardware. However, this should not be a problem as all common
> i2c-client communication does not rely on more than one repeated start.
>
> Changes since v11:
> - corrected wrong id_entry on sam9261 twi gpio pdev
>

Thanks for this new version, you can add
Tested-By: Ludovic Desroches <ludovic.desroches@atmel.com>
for the whole series.

Concerning the open drain issue, even if I don't have it on my board 
your patch is correct it is needed also for chips. Once I'll have the 
complete list, I'll send an additional patch.

Regards

Ludovic


> Nikolaus Voss (4):
>    drivers/i2c/busses/i2c-at91.c: remove old polling driver
>    Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
>    drivers/i2c/busses/i2c-at91.c: add new driver
>    G45 TWI: remove open drain setting for twi function gpios
>
>   arch/arm/mach-at91/at91rm9200.c            |    1 +
>   arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
>   arch/arm/mach-at91/at91sam9260.c           |    1 +
>   arch/arm/mach-at91/at91sam9261.c           |    1 +
>   arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
>   arch/arm/mach-at91/at91sam9263.c           |    1 +
>   arch/arm/mach-at91/at91sam9g45.c           |    2 +
>   arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
>   arch/arm/mach-at91/at91sam9rl.c            |    2 +
>   arch/arm/mach-at91/at91sam9x5.c            |    3 +
>   arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
>   drivers/i2c/busses/Kconfig                 |   11 +-
>   drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
>   13 files changed, 418 insertions(+), 287 deletions(-)
>   delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
>

[PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[Nikolaus Voss]

The old driver has two main deficencies:
i)  No repeated start (Sr) condiction is possible, this makes it unusable
    e.g. for most SMBus transfers.
ii) I/O was done with polling/busy waiting what caused over-/underruns
    even at light system loads and clock speeds.

The new driver overcomes these deficencies and in addition allows for
more than one TWI interface.

A remaining limitation is the fact, that only one repeated start is
possible (two concatenated messages). This limitation is imposed by
the hardware. However, this should not be a problem as all common
i2c-client communication does not rely on more than one repeated start.

Changes since v10:
 - fix for flags persistency suggested and tested by Carsten Behling
 - clk_lookup.dev_id entries for at91sam9x5
 - calc_twi_clock fix for sam9261 by Ludovic Desroches

Nikolaus Voss (4):
  drivers/i2c/busses/i2c-at91.c: remove old polling driver
  Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
  drivers/i2c/busses/i2c-at91.c: add new driver
  G45 TWI: remove open drain setting for twi function gpios

 arch/arm/mach-at91/at91rm9200.c            |    1 +
 arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
 arch/arm/mach-at91/at91sam9260.c           |    1 +
 arch/arm/mach-at91/at91sam9261.c           |    1 +
 arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
 arch/arm/mach-at91/at91sam9263.c           |    1 +
 arch/arm/mach-at91/at91sam9g45.c           |    2 +
 arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
 arch/arm/mach-at91/at91sam9rl.c            |    2 +
 arch/arm/mach-at91/at91sam9x5.c            |    3 +
 arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
 drivers/i2c/busses/Kconfig                 |   11 +-
 drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
 13 files changed, 418 insertions(+), 287 deletions(-)
 delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h

-- 
1.7.9.5

[PATCH v11 0/4] AT91: replace old i2c-at91.c TWI driver

[Nikolaus Voss]

The old driver has two main deficencies:
i)  No repeated start (Sr) condiction is possible, this makes it unusable
    e.g. for most SMBus transfers.
ii) I/O was done with polling/busy waiting what caused over-/underruns
    even at light system loads and clock speeds.

The new driver overcomes these deficencies and in addition allows for
more than one TWI interface.

A remaining limitation is the fact, that only one repeated start is
possible (two concatenated messages). This limitation is imposed by
the hardware. However, this should not be a problem as all common
i2c-client communication does not rely on more than one repeated start.

Changes since v10:
 - fix for flags persistency suggested and tested by Carsten Behling
 - clk_lookup.dev_id entries for at91sam9x5
 - calc_twi_clock fix for sam9261 by Ludovic Desroches

Nikolaus Voss (4):
  drivers/i2c/busses/i2c-at91.c: remove old polling driver
  Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
  drivers/i2c/busses/i2c-at91.c: add new driver
  G45 TWI: remove open drain setting for twi function gpios

 arch/arm/mach-at91/at91rm9200.c            |    1 +
 arch/arm/mach-at91/at91rm9200_devices.c    |    9 +
 arch/arm/mach-at91/at91sam9260.c           |    1 +
 arch/arm/mach-at91/at91sam9261.c           |    1 +
 arch/arm/mach-at91/at91sam9261_devices.c   |    9 +
 arch/arm/mach-at91/at91sam9263.c           |    1 +
 arch/arm/mach-at91/at91sam9g45.c           |    2 +
 arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
 arch/arm/mach-at91/at91sam9rl.c            |    2 +
 arch/arm/mach-at91/at91sam9x5.c            |    3 +
 arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
 drivers/i2c/busses/Kconfig                 |   11 +-
 drivers/i2c/busses/i2c-at91.c              |  591 ++++++++++++++++++----------
 13 files changed, 418 insertions(+), 287 deletions(-)
 delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h

-- 
1.7.9.5