ARM: Developed device driver for Atmel TSADC controller

Some Atmel AT91 devices contains a touchscreen analog to digital converter. This device driver use the ADC as a multi-channel raw data input device.

Tested on AT91SAM9G45 boards.

---
 CREDITS                                    |    4 +
 arch/arm/configs/at91sam9g45_defconfig     |    1 +
 arch/arm/mach-at91/include/mach/at91_adc.h |   16 ++
 drivers/misc/Kconfig                       |    7 +
 drivers/misc/Makefile                      |    1 +
 drivers/misc/atmel_tsadc.c                 |  361 ++++++++++++++++++++++++++++
 6 files changed, 390 insertions(+), 0 deletions(-)
 create mode 100644 drivers/misc/atmel_tsadc.c

index 370b4c7..8c615eb 100644
@@ -2652,6 +2652,10 @@ S: 2364 Old Trail Drive
 S: Reston, Virginia 20191
 S: USA
 
+N: Petter Nordby
+E: pettno at gmail.com
+D: Atmel ADC device driver
+
 N: Fredrik Noring
 E: noring at nocrew.org
 W: http://www.lysator.liu.se/~noring/

index 606d48f..748caca 100644
@@ -15,6 +15,7 @@ CONFIG_MODULE_UNLOAD=y
 # CONFIG_BLK_DEV_BSG is not set
 # CONFIG_IOSCHED_DEADLINE is not set
 # CONFIG_IOSCHED_CFQ is not set
+CONFIG_CROSS_COMPILE="arm-linux-"
 CONFIG_ARCH_AT91=y
 CONFIG_ARCH_AT91SAM9G45=y
 CONFIG_MACH_AT91SAM9M10G45EK=y

index 8e7ed5c..b665d61 100644
@@ -29,12 +29,28 @@
 #define		AT91_ADC_LOWRES		(1 << 4)	/* Low Resolution */
 #define		AT91_ADC_SLEEP		(1 << 5)	/* Sleep Mode */
 #define		AT91_ADC_PRESCAL	(0x3f << 8)	/* Prescalar Rate Selection */
+#define			AT91_ADC_EPRESCAL	(0xff << 8)	/* Prescalar Rate Selection (Extended) */
 #define			AT91_ADC_PRESCAL_(x)	((x) << 8)
 #define		AT91_ADC_STARTUP	(0x1f << 16)	/* Startup Up Time */
 #define			AT91_ADC_STARTUP_(x)	((x) << 16)
 #define		AT91_ADC_SHTIM		(0xf  << 24)	/* Sample & Hold Time */
 #define			AT91_ADC_SHTIM_(x)	((x) << 24)
 
+#define AT91_ADC_TRGR		0x08		/* Trigger register */
+#define		AT91_ADC_TRGMOD	(7      <<  0)	/* Trigger mode */
+#define			AT91_ADC_TRGMOD_NONE		(0 << 0)
+#define			AT91_ADC_TRGMOD_EXT_RISING	(1 << 0)
+#define			AT91_ADC_TRGMOD_EXT_FALLING	(2 << 0)
+#define			AT91_ADC_TRGMOD_EXT_ANY		(3 << 0)
+#define			AT91_ADC_TRGMOD_PENDET		(4 << 0)
+#define			AT91_ADC_TRGMOD_PERIOD		(5 << 0)
+#define			AT91_ADC_TRGMOD_CONTINUOUS	(6 << 0)
+#define			AT91_ADC_TRGPER	(0xffff << 16)	/* Trigger period */
+
+#define AT91_ADC_TSR	0x0C	/* Touch Screen register */
+#define	  AT91_ADC_TSFREQ	(0xf <<  0)	/* TS Frequency in Interleaved mode */
+#define	  AT91_ADC_TSSHTIM	(0xf << 24)	/* Sample & Hold time */
+
 #define AT91_ADC_CHER		0x10		/* Channel Enable Register */
 #define AT91_ADC_CHDR		0x14		/* Channel Disable Register */
 #define AT91_ADC_CHSR		0x18		/* Channel Status Register */

index 6a1a092..d105f42 100644
@@ -112,6 +112,13 @@ config ATMEL_TCB_CLKSRC_BLOCK
 	  TC can be used for other purposes, such as PWM generation and
 	  interval timing.
 
+config ATMEL_TSADC
+	tristate "Atmel touchscreen ADC char device driver"
+	depends on ARCH_AT91SAM9RL || ARCH_AT91SAM9G45
+	help
+	  Say Y here if you want to use the touchscreen ADC controller
+	  as a simple ADC input device.
+
 config IBM_ASM
 	tristate "Device driver for IBM RSA service processor"
 	depends on X86 && PCI && INPUT && EXPERIMENTAL

index 3e1d801..b6a13a1 100644
@@ -10,6 +10,7 @@ obj-$(CONFIG_INTEL_MID_PTI)	+= pti.o
 obj-$(CONFIG_ATMEL_PWM)		+= atmel_pwm.o
 obj-$(CONFIG_ATMEL_SSC)		+= atmel-ssc.o
 obj-$(CONFIG_ATMEL_TCLIB)	+= atmel_tclib.o
+obj-$(CONFIG_ATMEL_TSADC)	+= atmel_tsadc.o
 obj-$(CONFIG_BMP085)		+= bmp085.o
 obj-$(CONFIG_ICS932S401)	+= ics932s401.o
 obj-$(CONFIG_LKDTM)		+= lkdtm.o

1.7.7

Shouldn't this be in MAINTAINERS?

We have a proper abstraction of input devices under drivers/input which includes touchscreens. I suggest using that rather than developing your own private kernel API.

It will avoid all sorts of bugs, like using put_user() with IRQs disabled.

Thanks.

On 01/23/2012 12:36 PM, Russell King - ARM Linux :

Petter,

Be sure that I appreciate the submission of your work. Examples of code and new drivers are always a big strength of the Open Source community.

But as Russell suggested, this use of ADC for AT91SAM9G45 family (TSADC) will be better suited for the IIO subsystem.
A new AT91 ADC driver designed for this IIO subsystem has been developed a little time ago:
"[PATCH RESEND v13] AT91: Add a driver for the ADC"

It will likely be included shortly in mainline kernel. I advice to follow this development and add the support of SAM9G45 ADC to this existing infrastructure.

I guess that the input/touchsreen part of the TSADC is not the purpose of your driver:
drivers/input/touchscreen/atmel_tsadcc.c
will take care of this feature.

Best regards,

Nicolas Ferre

Thanks for pointing me in this direction. Exactly what I need. I'm really looking forward to getting it in mainline kernel.

Best regards,
Petter Nordby