iio: adc: exynos_adc: add support for s3c64xx adc

The ADC in s3c64xx is almost the same as exynosv1, but
has a different 'select' method. Adding this here will be
helpful to move over the existing s3c64xx platform from the
legacy plat-samsung/adc driver to the new exynos-adc.

Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Chanwoo Choi <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt

···
 				future controllers.
 			Must be "samsung,exynos3250-adc" for
 				controllers compatible with ADC of Exynos3250.
+			Must be "samsung,s3c6410-adc" for
+				the ADC in s3c6410 and compatibles
 - reg:			Contains ADC register address range (base address and
 			length) and the address of the phy enable register.
 - interrupts: 		Contains the interrupt information for the timer. The

drivers/iio/adc/exynos_adc.c

···
 #include <linux/iio/machine.h>
 #include <linux/iio/driver.h>
 
-/* EXYNOS4412/5250 ADC_V1 registers definitions */
+/* S3C/EXYNOS4412/5250 ADC_V1 registers definitions */
 #define ADC_V1_CON(x)		((x) + 0x00)
 #define ADC_V1_DLY(x)		((x) + 0x08)
 #define ADC_V1_DATX(x)		((x) + 0x0C)
···
 #define ADC_V1_CON_PRSCEN	(1u << 14)
 #define ADC_V1_CON_PRSCLV(x)	(((x) & 0xFF) << 6)
 #define ADC_V1_CON_STANDBY	(1u << 2)
+
+/* Bit definitions for S3C2410 ADC */
+#define ADC_S3C2410_CON_SELMUX(x) (((x) & 7) << 3)
 
 /* Bit definitions for ADC_V2 */
 #define ADC_V2_CON1_SOFT_RESET	(1u << 2)
···
 	.start_conv	= exynos_adc_v1_start_conv,
 };
 
+static void exynos_adc_s3c64xx_start_conv(struct exynos_adc *info,
+					  unsigned long addr)
+{
+	u32 con1;
+
+	con1 = readl(ADC_V1_CON(info->regs));
+	con1 &= ~ADC_S3C2410_CON_SELMUX(0x7);
+	con1 |= ADC_S3C2410_CON_SELMUX(addr);
+	writel(con1 | ADC_CON_EN_START, ADC_V1_CON(info->regs));
+}
+
+static struct exynos_adc_data const exynos_adc_s3c64xx_data = {
+	.num_channels	= MAX_ADC_V1_CHANNELS,
+
+	.init_hw	= exynos_adc_v1_init_hw,
+	.exit_hw	= exynos_adc_v1_exit_hw,
+	.clear_irq	= exynos_adc_v1_clear_irq,
+	.start_conv	= exynos_adc_s3c64xx_start_conv,
+};
+
 static void exynos_adc_v2_init_hw(struct exynos_adc *info)
 {
 	u32 con1, con2;
···
 
 static const struct of_device_id exynos_adc_match[] = {
 	{
+		.compatible = "samsung,s3c6410-adc",
+		.data = &exynos_adc_s3c64xx_data,
+	}, {
 		.compatible = "samsung,exynos-adc-v1",
 		.data = &exynos_adc_v1_data,
 	}, {