[PATCH] i2c-designware: Interrupt sharing and SDA hold time

* [PATCH] i2c-designware: Interrupt sharing and SDA hold time
@ 2013-02-15 10:11 ` Christian Ruppert
  0 siblings, 0 replies; 13+ messages in thread
From: Christian Ruppert @ 2013-02-15 10:11 UTC (permalink / raw)
  To: Wolfram Sang, Ben Dooks (embedded platforms)
  Cc: Grant Likely, Rob Herring, Rob Landley, devicetree-discuss,
	linux-doc, linux-kernel, linux-i2c, Vineet Gupta,
	Christian Ruppert, Pierrick Hascoet

This patch implements interrupt sharing and SDA hold time configuration in
the designware i2c driver. Both functions are enabled through platform data
or device tree. Tested with Linux-3.8rc4 (Synopsys ARC port, see
https://github.com/foss-for-synopsys-dwc-arc-processors/linux/commits/arc-3.8-baseline).

Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com>
Signed-off-by: Pierrick Hascoet <pierrick.hascoet@abilis.com>
---
 .../devicetree/bindings/i2c/i2c-designware.txt     |   18 ++++++++++
 drivers/i2c/busses/i2c-designware-core.c           |    6 +++
 drivers/i2c/busses/i2c-designware-core.h           |    2 +
 drivers/i2c/busses/i2c-designware-platdrv.c        |   34 +++++++++++++++++++-
 include/linux/i2c/i2c-designware.h                 |   13 +++++++
 5 files changed, 72 insertions(+), 1 deletions(-)
 create mode 100644 include/linux/i2c/i2c-designware.h

diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
index e42a2ee..474386b 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
@@ -10,6 +10,12 @@ Recommended properties :
 
  - clock-frequency : desired I2C bus clock frequency in Hz.
 
+Optional properties :
+ - interrupts-shared : If this property is present, the interrupt line is
+   considered shared with other devices.
+ - sda-hold-time : If this property is present, the register SDA_HOLD will
+   be initialised with its value.
+
 Example :
 
 	i2c@f0000 {
@@ -20,3 +26,15 @@ Example :
 		interrupts = <11>;
 		clock-frequency = <400000>;
 	};
+
+	i2c@1120000 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		compatible = "snps,designware-i2c";
+		reg = <0x1120000 0x1000>;
+		interrupt-parent = <&ictl>;
+		interrupts = <12 1>;
+		interrupts-shared;
+		clock-frequency = <400000>;
+		sda-hold-time = <0x64>;
+	};
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index cbba7db..36ba0b5 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -34,6 +34,7 @@
 #include <linux/io.h>
 #include <linux/pm_runtime.h>
 #include <linux/delay.h>
+#include <linux/i2c/i2c-designware.h>
 #include "i2c-designware-core.h"
 
 /*
@@ -66,6 +67,7 @@
 #define DW_IC_STATUS		0x70
 #define DW_IC_TXFLR		0x74
 #define DW_IC_RXFLR		0x78
+#define DW_IC_SDA_HOLD		0x7c
 #define DW_IC_TX_ABRT_SOURCE	0x80
 #define DW_IC_COMP_PARAM_1	0xf4
 #define DW_IC_COMP_TYPE		0xfc
@@ -309,6 +311,10 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
 	dw_writel(dev, lcnt, DW_IC_FS_SCL_LCNT);
 	dev_dbg(dev->dev, "Fast-mode HCNT:LCNT = %d:%d\n", hcnt, lcnt);
 
+	/* Configure SDA Hold Time if required */
+	if (dev->pdat_flags & I2C_DW_PDAT_FLAGS_SET_HOLDTIME)
+		dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);
+
 	/* Configure Tx/Rx FIFO threshold levels */
 	dw_writel(dev, dev->tx_fifo_depth - 1, DW_IC_TX_TL);
 	dw_writel(dev, 0, DW_IC_RX_TL);
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 9c1840e..ef20477 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -88,6 +88,8 @@ struct dw_i2c_dev {
 	u32			master_cfg;
 	unsigned int		tx_fifo_depth;
 	unsigned int		rx_fifo_depth;
+	u32			sda_hold_time;
+	unsigned int		pdat_flags;
 };
 
 #define ACCESS_SWAP		0x00000001
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 343357a..2ad2da3 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -34,11 +34,13 @@
 #include <linux/sched.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
+#include <linux/of.h>
 #include <linux/of_i2c.h>
 #include <linux/platform_device.h>
 #include <linux/pm.h>
 #include <linux/io.h>
 #include <linux/slab.h>
+#include <linux/i2c/i2c-designware.h>
 #include "i2c-designware-core.h"
 
 static struct i2c_algorithm i2c_dw_algo = {
@@ -56,6 +58,28 @@ static int dw_i2c_probe(struct platform_device *pdev)
 	struct i2c_adapter *adap;
 	struct resource *mem, *ioarea;
 	int irq, r;
+	unsigned long irqf;
+	struct i2c_designware_platform_data *pdat = pdev->dev.platform_data;
+
+	if ((!pdat) && pdev->dev.of_node) {
+		struct device_node *node = pdev->dev.of_node;
+
+		pdat = kmalloc(sizeof(struct i2c_designware_platform_data),
+				GFP_KERNEL);
+		if (!pdat)
+			return -ENOMEM;
+
+		pdat->flags = 0;
+
+		if (of_get_property(node, "interrupts-shared", NULL))
+			pdat->flags |= I2C_DW_PDAT_FLAGS_SHARE_IRQ;
+
+		if (!of_property_read_u32(node, "sda-hold-time",
+					&pdat->sda_hold_time))
+			pdat->flags |= I2C_DW_PDAT_FLAGS_SET_HOLDTIME;
+
+		pdev->dev.platform_data = pdat;
+	}
 
 	/* NOTE: driver uses the static register mapping */
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -120,12 +144,20 @@ static int dw_i2c_probe(struct platform_device *pdev)
 		dev->tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
 		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
 	}
+	dev->sda_hold_time = pdat->sda_hold_time;
+	dev->pdat_flags = pdat->flags;
+
 	r = i2c_dw_init(dev);
 	if (r)
 		goto err_iounmap;
 
 	i2c_dw_disable_int(dev);
-	r = request_irq(dev->irq, i2c_dw_isr, IRQF_DISABLED, pdev->name, dev);
+
+	irqf = IRQF_DISABLED;
+	if (dev->pdat_flags & I2C_DW_PDAT_FLAGS_SHARE_IRQ)
+		irqf |= IRQF_SHARED;
+
+	r = request_irq(dev->irq, i2c_dw_isr, irqf, pdev->name, dev);
 	if (r) {
 		dev_err(&pdev->dev, "failure requesting irq %i\n", dev->irq);
 		goto err_iounmap;
diff --git a/include/linux/i2c/i2c-designware.h b/include/linux/i2c/i2c-designware.h
new file mode 100644
index 0000000..ea8192a
--- /dev/null
+++ b/include/linux/i2c/i2c-designware.h
@@ -0,0 +1,13 @@
+#ifndef __I2C_DESIGNWARE_H__
+#define __I2C_DESIGNWARE_H__
+
+#include <linux/platform_device.h>
+
+struct i2c_designware_platform_data {
+	unsigned int flags;
+#define I2C_DW_PDAT_FLAGS_SHARE_IRQ    (1L<<0)
+#define I2C_DW_PDAT_FLAGS_SET_HOLDTIME (1L<<1)
+	u32          sda_hold_time;
+};
+
+#endif /* __I2C_DESIGNWARE_H__ */
-- 
1.7.1


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