Merge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/ker…

…nel/git/wsa/linux

Pull i2c changes from Wolfram Sang:

 - an arbitration driver.  While the driver is quite simple, it caused
   discussion if we need additional arbitration on top of the one
   specified in the I2C standard.  Conclusion is that I accept a few
   generic mechanisms, but not very specific ones.

 - the core lost the detach_adapter() call.  It has no users anymore and
   was in the way for other cleanups.  attach_adapter() is sadly still
   there since there are users waiting to be converted.

 - the core gained a bus recovery infrastructure.  I2C defines a way to
   recover if the data line is stalled.  This mechanism is now in the
   core and drivers can now pass some data to make use of it.

 - bigger driver cleanups for designware, s3c2410

 - removing superfluous refcounting from drivers

 - removing Ben Dooks as second maintainer due to inactivity.  Thanks
   for all your work so far, Ben!

 - bugfixes, feature additions, devicetree fixups, simplifications...

* 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (38 commits)
  i2c: xiic: must always write 16-bit words to TX_FIFO
  i2c: octeon: use HZ in timeout value
  i2c: octeon: Fix i2c fail problem when a process is terminated by a signal
  i2c: designware-pci: drop superfluous {get|put}_device
  i2c: designware-plat: drop superfluous {get|put}_device
  i2c: davinci: drop superfluous {get|put}_device
  MAINTAINERS: Ben Dooks is inactive regarding I2C
  i2c: mux: Add i2c-arb-gpio-challenge 'mux' driver
  i2c: at91: convert to dma_request_slave_channel_compat()
  i2c: mxs: do error checking and handling in PIO mode
  i2c: mxs: remove races in PIO code
  i2c-designware: switch to use runtime PM autosuspend
  i2c-designware: use usleep_range() in the busy-loop
  i2c-designware: enable/disable the controller properly
  i2c-designware: use dynamic adapter numbering on Lynxpoint
  i2c-designware-pci: use managed functions pcim_* and devm_*
  i2c-designware-pci: use dev_err() instead of printk()
  i2c-designware: move to managed functions (devm_*)
  i2c: remove CONFIG_HOTPLUG ifdefs
  i2c: s3c2410: Add SMBus emulation for block read
  ...

Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt

@@ -0,0 +1,80 @@
+GPIO-based I2C Arbitration Using a Challenge & Response Mechanism
+=================================================================
+This uses GPIO lines and a challenge & response mechanism to arbitrate who is
+the master of an I2C bus in a multimaster situation.
+
+In many cases using GPIOs to arbitrate is not needed and a design can use
+the standard I2C multi-master rules.  Using GPIOs is generally useful in
+the case where there is a device on the bus that has errata and/or bugs
+that makes standard multimaster mode not feasible.
+
+
+Algorithm:
+
+All masters on the bus have a 'bus claim' line which is an output that the
+others can see. These are all active low with pull-ups enabled.  We'll
+describe these lines as:
+
+- OUR_CLAIM: output from us signaling to other hosts that we want the bus
+- THEIR_CLAIMS: output from others signaling that they want the bus
+
+The basic algorithm is to assert your line when you want the bus, then make
+sure that the other side doesn't want it also.  A detailed explanation is best
+done with an example.
+
+Let's say we want to claim the bus.  We:
+1. Assert OUR_CLAIM.
+2. Waits a little bit for the other sides to notice (slew time, say 10
+   microseconds).
+3. Check THEIR_CLAIMS.  If none are asserted then the we have the bus and we are
+   done.
+4. Otherwise, wait for a few milliseconds and see if THEIR_CLAIMS are released.
+5. If not, back off, release the claim and wait for a few more milliseconds.
+6. Go back to 1 (until retry time has expired).
+
+
+Required properties:
+- compatible: i2c-arb-gpio-challenge
+- our-claim-gpio: The GPIO that we use to claim the bus.
+- their-claim-gpios: The GPIOs that the other sides use to claim the bus.
+  Note that some implementations may only support a single other master.
+- Standard I2C mux properties. See mux.txt in this directory.
+- Single I2C child bus node at reg 0. See mux.txt in this directory.
+
+Optional properties:
+- slew-delay-us: microseconds to wait for a GPIO to go high. Default is 10 us.
+- wait-retry-us: we'll attempt another claim after this many microseconds.
+    Default is 3000 us.
+- wait-free-us: we'll give up after this many microseconds. Default is 50000 us.
+
+
+Example:
+	i2c@12CA0000 {
+		compatible = "acme,some-i2c-device";
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};
+
+	i2c-arbitrator {
+		compatible = "i2c-arb-gpio-challenge";
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		i2c-parent = <&{/i2c@12CA0000}>;
+
+		our-claim-gpio = <&gpf0 3 1>;
+		their-claim-gpios = <&gpe0 4 1>;
+		slew-delay-us = <10>;
+		wait-retry-us = <3000>;
+		wait-free-us = <50000>;
+
+		i2c@0 {
+			reg = <0>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			i2c@52 {
+				// Normal I2C device
+			};
+		};
+	};

MAINTAINERS

@@ -3919,7 +3919,6 @@ F:	drivers/i2c/i2c-stub.c
 
 I2C SUBSYSTEM
 M:	Wolfram Sang <wsa@the-dreams.de>
-M:	"Ben Dooks (embedded platforms)" <ben-linux@fluff.org>
 L:	linux-i2c@vger.kernel.org
 W:	http://i2c.wiki.kernel.org/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git

arch/arm/mach-s3c24xx/mach-rx1950.c

@@ -56,7 +56,6 @@
 #include <plat/cpu.h>
 #include <plat/devs.h>
 #include <plat/pm.h>
-#include <plat/regs-iic.h>
 #include <plat/regs-serial.h>
 
 #include "common.h"

arch/arm/mach-tegra/tegra.c

@@ -31,8 +31,6 @@
 #include <linux/pda_power.h>
 #include <linux/platform_data/tegra_usb.h>
 #include <linux/io.h>
-#include <linux/i2c.h>
-#include <linux/i2c-tegra.h>
 #include <linux/slab.h>
 #include <linux/sys_soc.h>
 #include <linux/usb/tegra_usb_phy.h>

arch/arm/plat-samsung/devs.c

@@ -63,7 +63,6 @@
 #include <linux/platform_data/usb-s3c2410_udc.h>
 #include <linux/platform_data/usb-ohci-s3c2410.h>
 #include <plat/usb-phy.h>
-#include <plat/regs-iic.h>
 #include <plat/regs-serial.h>
 #include <plat/regs-spi.h>
 #include <linux/platform_data/spi-s3c64xx.h>

drivers/gpu/drm/gma500/oaktrail_hdmi_i2c.c

@@ -319,8 +319,7 @@ void oaktrail_hdmi_i2c_exit(struct pci_dev *dev)
 	struct hdmi_i2c_dev *i2c_dev;
 
 	hdmi_dev = pci_get_drvdata(dev);
-	if (i2c_del_adapter(&oaktrail_hdmi_i2c_adapter))
-		DRM_DEBUG_DRIVER("Failed to delete hdmi-i2c adapter\n");
+	i2c_del_adapter(&oaktrail_hdmi_i2c_adapter);
 
 	i2c_dev = hdmi_dev->i2c_dev;
 	kfree(i2c_dev);

drivers/i2c/busses/i2c-amd756-s4882.c

@@ -169,11 +169,7 @@ static int __init amd756_s4882_init(void)
 	}
 
 	/* Unregister physical bus */
-	error = i2c_del_adapter(&amd756_smbus);
-	if (error) {
-		dev_err(&amd756_smbus.dev, "Physical bus removal failed\n");
-		goto ERROR0;
-	}
+	i2c_del_adapter(&amd756_smbus);
 
 	printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n");
 	/* Define the 5 virtual adapters and algorithms structures */

drivers/i2c/busses/i2c-at91.c

@@ -603,15 +603,18 @@ static const struct of_device_id atmel_twi_dt_ids[] = {
 	}
 };
 MODULE_DEVICE_TABLE(of, atmel_twi_dt_ids);
-#else
-#define atmel_twi_dt_ids NULL
 #endif
 
-static bool filter(struct dma_chan *chan, void *slave)
+static bool filter(struct dma_chan *chan, void *pdata)
 {
-	struct at_dma_slave *sl = slave;
+	struct at91_twi_pdata *sl_pdata = pdata;
+	struct at_dma_slave *sl;
+
+	if (!sl_pdata)
+		return false;
 
-	if (sl->dma_dev == chan->device->dev) {
+	sl = &sl_pdata->dma_slave;
+	if (sl && (sl->dma_dev == chan->device->dev)) {
 		chan->private = sl;
 		return true;
 	} else {
@@ -622,11 +625,10 @@ static bool filter(struct dma_chan *chan, void *slave)
 static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
 {
 	int ret = 0;
-	struct at_dma_slave *sdata;
+	struct at91_twi_pdata *pdata = dev->pdata;
 	struct dma_slave_config slave_config;
 	struct at91_twi_dma *dma = &dev->dma;
-
-	sdata = &dev->pdata->dma_slave;
+	dma_cap_mask_t mask;
 
 	memset(&slave_config, 0, sizeof(slave_config));
 	slave_config.src_addr = (dma_addr_t)phy_addr + AT91_TWI_RHR;
@@ -637,25 +639,22 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
 	slave_config.dst_maxburst = 1;
 	slave_config.device_fc = false;
 
-	if (sdata && sdata->dma_dev) {
-		dma_cap_mask_t mask;
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
 
-		dma_cap_zero(mask);
-		dma_cap_set(DMA_SLAVE, mask);
-		dma->chan_tx = dma_request_channel(mask, filter, sdata);
-		if (!dma->chan_tx) {
-			dev_err(dev->dev, "no DMA channel available for tx\n");
-			ret = -EBUSY;
-			goto error;
-		}
-		dma->chan_rx = dma_request_channel(mask, filter, sdata);
-		if (!dma->chan_rx) {
-			dev_err(dev->dev, "no DMA channel available for rx\n");
-			ret = -EBUSY;
-			goto error;
-		}
-	} else {
-		ret = -EINVAL;
+	dma->chan_tx = dma_request_slave_channel_compat(mask, filter, pdata,
+							dev->dev, "tx");
+	if (!dma->chan_tx) {
+		dev_err(dev->dev, "can't get a DMA channel for tx\n");
+		ret = -EBUSY;
+		goto error;
+	}
+
+	dma->chan_rx = dma_request_slave_channel_compat(mask, filter, pdata,
+							dev->dev, "rx");
+	if (!dma->chan_rx) {
+		dev_err(dev->dev, "can't get a DMA channel for rx\n");
+		ret = -EBUSY;
 		goto error;
 	}
 
@@ -785,12 +784,11 @@ static int at91_twi_probe(struct platform_device *pdev)
 static int at91_twi_remove(struct platform_device *pdev)
 {
 	struct at91_twi_dev *dev = platform_get_drvdata(pdev);
-	int rc;
 
-	rc = i2c_del_adapter(&dev->adapter);
+	i2c_del_adapter(&dev->adapter);
 	clk_disable_unprepare(dev->clk);
 
-	return rc;
+	return 0;
 }
 
 #ifdef CONFIG_PM
@@ -828,7 +826,7 @@ static struct platform_driver at91_twi_driver = {
 	.driver		= {
 		.name	= "at91_i2c",
 		.owner	= THIS_MODULE,
-		.of_match_table = atmel_twi_dt_ids,
+		.of_match_table = of_match_ptr(atmel_twi_dt_ids),
 		.pm	= at91_twi_pm_ops,
 	},
 };

drivers/i2c/busses/i2c-cbus-gpio.c

@@ -206,7 +206,9 @@ static int cbus_i2c_remove(struct platform_device *pdev)
 {
 	struct i2c_adapter *adapter = platform_get_drvdata(pdev);
 
-	return i2c_del_adapter(adapter);
+	i2c_del_adapter(adapter);
+
+	return 0;
 }
 
 static int cbus_i2c_probe(struct platform_device *pdev)