[PATCH v2] input: touchscreen: add OF match table for ads7846

The current ads7846 has no OF match table. The method used is by applying a heuristic (of_modalias_node) which tries to name the device in a way that will match an existing device driver.
This patch adds explicit OF match table for ads7846, then the normal device tree match behaviour will always work.
It has been tested on PRIMA2 EVB board of CSR with a SPI's child node like the below:
ts@0 {
        compatible = "ti,ads7845";
        reg = <0x0>;
        spi-max-frequency = <31250>;
        interrupts = <90>;
};

Signed-off-by: Barry Song <redacted>
Cc: Thomas Chou <redacted>
Acked-by: Grant Likely <redacted>
---
 .../devicetree/bindings/input/ads7846.txt          |   20 ++++++++++++++++++++
 drivers/input/touchscreen/ads7846.c                |   14 ++++++++++++++
 2 files changed, 34 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/input/ads7846.txt

diff --git a/Documentation/devicetree/bindings/input/ads7846.txt b/Documentation/devicetree/bindings/input/ads7846.txt
new file mode 100644
index 0000000..36c1fd0
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/ads7846.txt

@@ -0,0 +1,20 @@
+ADS7846/ADS7845/ADS7843 touchscreen connected to a SPI bus
+
+Required properties:
+- compatible : should be "ti,ads7846", "ti,ads7845" or "ti,ads7843"
+- reg : should specify SPI address (chip-select number).
+- spi-max-frequency : maximum frequency for this device (Hz).
+- interrupts : the interrupt of pendown.
+
+Optional properties:
+- interrupt-parent : the phandle for the interrupt controller that
+  services interrupts for this device.
+
+Example:
+
+	ts@0 {
+		compatible = "ti,ads7845",
+		reg = <0>;
+		spi-max-frequency = <31250>;
+		interrupts = <90>;
+	};

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 5196861..fa9345c 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c

@@ -28,6 +28,7 @@
 #include <linux/slab.h>
 #include <linux/pm.h>
 #include <linux/gpio.h>
+#include <linux/of.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/ads7846.h>
 #include <linux/regulator/consumer.h>

@@ -1425,12 +1426,25 @@ static int __devexit ads7846_remove(struct spi_device *spi)
 	return 0;
 }
 
+#if defined(CONFIG_OF)
+static struct of_device_id ads7846_spi_of_match_table[] __devinitdata = {
+	{ .compatible = "ti,ads7846", },
+	{ .compatible = "ti,ads7845", },
+	{ .compatible = "ti,ads7843", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ads7846_spi_of_match_table);
+#else
+#define ads7846_spi_of_match_table NULL
+#endif
+
 static struct spi_driver ads7846_driver = {
 	.driver = {
 		.name	= "ads7846",
 		.bus	= &spi_bus_type,
 		.owner	= THIS_MODULE,
 		.pm	= &ads7846_pm,
+		.of_match_table = ads7846_spi_of_match_table,
 	},
 	.probe		= ads7846_probe,
 	.remove		= __devexit_p(ads7846_remove),

-- 
1.7.1



Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom
More information can be found at www.csr.com. Follow CSR on Twitter at http://twitter.com/CSR_PLC and read our blog at www.csr.com/blog

On 06/14/2011 09:45 AM, Barry Song wrote:

The current ads7846 has no OF match table. The method used is by applying a heuristic (of_modalias_node) which tries to name the device in a way that will match an existing device driver.
This patch adds explicit OF match table for ads7846, then the normal device tree match behaviour will always work.
It has been tested on PRIMA2 EVB board of CSR with a SPI's child node like the below:
ts@0 {
         compatible = "ti,ads7845";
         reg =<0x0>;
         spi-max-frequency =<31250>;
         interrupts =<90>;
};

Hi Barry,

Thank you very much for your help. Could we add an option for gpio 
pendown, like this?

- gpios : should specify GPIO used for pendown.

If interrupt node is not present in this node, gpio_to_irq of the pen
down GPIO will be used.

Best regards,
Thomas

Hi Thomas,
Thanks.

-----Original Message-----
From: Thomas Chou [mailto:thomas@wytron.com.tw]
Sent: 2011年6月14日 14:15
To: Baohua Song
Cc: dmitry.torokhov@gmail.com; linux-input@vger.kernel.org; DL-SHA-APBU
Linux; Junyi Zhang; Grant Likely
Subject: Re: [PATCH v2] input: touchscreen: add OF match table for ads7846

On 06/14/2011 09:45 AM, Barry Song wrote:

quoted

The current ads7846 has no OF match table. The method used is by applying a

heuristic (of_modalias_node) which tries to name the device in a way that will
match an existing device driver.

quoted

This patch adds explicit OF match table for ads7846, then the normal device

tree match behaviour will always work.

quoted

It has been tested on PRIMA2 EVB board of CSR with a SPI's child node like

the below:

quoted

ts@0 {
         compatible = "ti,ads7845";
         reg =<0x0>;
         spi-max-frequency =<31250>;
         interrupts =<90>;
};

Hi Barry,

Thank you very much for your help. 

You are welcome :-)

Could we add an option for gpio
pendown, like this?

- gpios : should specify GPIO used for pendown.

If interrupt node is not present in this node, gpio_to_irq of the pen
down GPIO will be used.

I disagree... An optional gpio node doesn't make sense here. The result of gpio_to_irq is still an interrupt, then we can place the result in interrupt node.
And the ads7846 driver required an interrupt node but not a gpio node since we don't find any of_get_gpio() in this driver. 
BTW, it even doesn’t make sense to call function gpio_to_irq in a driver like ads7846. on the contrary, drivers/input/keyboard/gpio_keys.c is really an good user of gpio_to_irq.

Best regards,
Thomas

-barry


Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom
More information can be found at www.csr.com. Follow CSR on Twitter at http://twitter.com/CSR_PLC and read our blog at www.csr.com/blog

On 06/14/2011 02:38 PM, Baohua Song wrote:

quoted

Could we add an option for gpio
pendown, like this?

- gpios : should specify GPIO used for pendown.

If interrupt node is not present in this node, gpio_to_irq of the pen
down GPIO will be used.

I disagree... An optional gpio node doesn't make sense here. The result of gpio_to_irq is still an interrupt, then we can place the result in interrupt node.
And the ads7846 driver required an interrupt node but not a gpio node since we don't find any of_get_gpio() in this driver.
BTW, it even doesn’t make sense to call function gpio_to_irq in a driver like ads7846. on the contrary, drivers/input/keyboard/gpio_keys.c is really an good user of gpio_to_irq.

Hi Barry,

The classical platform data is seldom used when device tree is passed.
So it would be better to disable platform data passing to verify device
tree support.

Without platform data passing, we don't have pdata and
pdata->get_pendown_state func for ads7846_setup_pendown(). The
ads7846_probe() will need updates on this.

Passing gpio for pendown might be a possible solution, as device tree
supports "gpios" node. We could use of_get_gpio_flags() to retrieve it.

I sent an earlier work of mine on this back in Feb. to you.

Best regards,
Thomas

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Hi Thomas,

-----Original Message-----
From: linux-input-owner@vger.kernel.org
[mailto:linux-input-owner@vger.kernel.org] On Behalf Of Thomas Chou
Sent: 2011年6月15日 12:02
To: Baohua Song
Cc: dmitry.torokhov@gmail.com; linux-input@vger.kernel.org; DL-SHA-APBU
Linux; Junyi Zhang; Grant Likely
Subject: Re: [PATCH v2] input: touchscreen: add OF match table for ads7846

On 06/14/2011 02:38 PM, Baohua Song wrote:

quoted

quoted

Could we add an option for gpio
pendown, like this?

- gpios : should specify GPIO used for pendown.

If interrupt node is not present in this node, gpio_to_irq of the pen
down GPIO will be used.

I disagree... An optional gpio node doesn't make sense here. The result of

gpio_to_irq is still an interrupt, then we can place the result in interrupt node.

quoted

And the ads7846 driver required an interrupt node but not a gpio node since

we don't find any of_get_gpio() in this driver.

quoted

BTW, it even doesn’t make sense to call function gpio_to_irq in a driver like

ads7846. on the contrary, drivers/input/keyboard/gpio_keys.c is really an good
user of gpio_to_irq.

Hi Barry,

The classical platform data is seldom used when device tree is passed.
So it would be better to disable platform data passing to verify device
tree support.

Without platform data passing, we don't have pdata and
pdata->get_pendown_state func for ads7846_setup_pendown(). The
ads7846_probe() will need updates on this.

Now the pdata has many fields and several hardware-special callback functions. Non-callback fields can be OF property but callbacks are difficult to be handled in DT. 
So for the moment, we use notifier_block to set pdata in board file as below

static int prima2_touchscreen_notifier_call(struct notifier_block *nb,
                                        unsigned long event, void *__dev)
{
        struct device *dev = __dev;
        struct spi_device *spi = to_spi_device(dev);

        if ((event == BUS_NOTIFY_ADD_DEVICE) &&
            of_device_is_compatible(dev->of_node, "ti,ads7845")) {
                spi->controller_data = &ads7845_ctrldata;
                dev->platform_data = &prima2_ads7845_pdata;
                return NOTIFY_OK;
        }   
        return NOTIFY_DONE;
}

static struct notifier_block prima2_touchscreen_nb = { 
        .notifier_call = prima2_touchscreen_notifier_call,
};

static void __init prima2_touchscreen_init(void)
{
        bus_register_notifier(&spi_bus_type, &prima2_touchscreen_nb);
}

Passing gpio for pendown might be a possible solution, as device tree
supports "gpios" node. We could use of_get_gpio_flags() to retrieve it.

Yes. Since ads7846 must read pendown gpio to get pendown status, gpio is necessary to ads7846 and interrupt is probably repeated copy of gpio since we can get it by gpio_to_irq().
gpio field in pdata may be deleted and moved to DT. that can be another patch after this one is merged. I maybe send it later

I sent an earlier work of mine on this back in Feb. to you.

Best regards,
Thomas

-barry



Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom
More information can be found at www.csr.com. Follow CSR on Twitter at http://twitter.com/CSR_PLC and read our blog at www.csr.com/blog