iio: adc: exynos_adc: Control special clock of ADC to support Exynos3250 ADC

This patch control special clock for ADC in Exynos series's FSYS block.
If special clock of ADC is registerd on clock list of common clk framework,
Exynos ADC drvier have to control this clock.

Exynos3250/Exynos4/Exynos5 has 'adc' clock as following:
- 'adc' clock: bus clock for ADC

Exynos3250 has additional 'sclk_adc' clock as following:
- 'sclk_adc' clock: special clock for ADC which provide clock to internal ADC

Exynos 4210/4212/4412 and Exynos5250/5420 has not included 'sclk_adc' clock
in FSYS_BLK. But, Exynos3250 based on Cortex-A7 has only included 'sclk_adc'
clock in FSYS_BLK.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/exynos_adc.c

@@ -24,6 +24,7 @@
 #include <linux/platform_device.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
+#include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/io.h>
@@ -70,8 +71,9 @@
 #define ADC_V2_CON2_ACH_SEL(x)	(((x) & 0xF) << 0)
 #define ADC_V2_CON2_ACH_MASK	0xF
 
-#define MAX_ADC_V2_CHANNELS	10
-#define MAX_ADC_V1_CHANNELS	8
+#define MAX_ADC_V2_CHANNELS		10
+#define MAX_ADC_V1_CHANNELS		8
+#define MAX_EXYNOS3250_ADC_CHANNELS	2
 
 /* Bit definitions common for ADC_V1 and ADC_V2 */
 #define ADC_CON_EN_START	(1u << 0)
@@ -81,9 +83,11 @@
 
 struct exynos_adc {
 	struct exynos_adc_data	*data;
+	struct device		*dev;
 	void __iomem		*regs;
 	void __iomem		*enable_reg;
 	struct clk		*clk;
+	struct clk		*sclk;
 	unsigned int		irq;
 	struct regulator	*vdd;
 
@@ -95,6 +99,7 @@ struct exynos_adc {
 
 struct exynos_adc_data {
 	int num_channels;
+	bool needs_sclk;
 
 	void (*init_hw)(struct exynos_adc *info);
 	void (*exit_hw)(struct exynos_adc *info);
@@ -102,6 +107,66 @@ struct exynos_adc_data {
 	void (*start_conv)(struct exynos_adc *info, unsigned long addr);
 };
 
+static void exynos_adc_unprepare_clk(struct exynos_adc *info)
+{
+	if (info->data->needs_sclk)
+		clk_unprepare(info->sclk);
+	clk_unprepare(info->clk);
+}
+
+static int exynos_adc_prepare_clk(struct exynos_adc *info)
+{
+	int ret;
+
+	ret = clk_prepare(info->clk);
+	if (ret) {
+		dev_err(info->dev, "failed preparing adc clock: %d\n", ret);
+		return ret;
+	}
+
+	if (info->data->needs_sclk) {
+		ret = clk_prepare(info->sclk);
+		if (ret) {
+			clk_unprepare(info->clk);
+			dev_err(info->dev,
+				"failed preparing sclk_adc clock: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static void exynos_adc_disable_clk(struct exynos_adc *info)
+{
+	if (info->data->needs_sclk)
+		clk_disable(info->sclk);
+	clk_disable(info->clk);
+}
+
+static int exynos_adc_enable_clk(struct exynos_adc *info)
+{
+	int ret;
+
+	ret = clk_enable(info->clk);
+	if (ret) {
+		dev_err(info->dev, "failed enabling adc clock: %d\n", ret);
+		return ret;
+	}
+
+	if (info->data->needs_sclk) {
+		ret = clk_enable(info->sclk);
+		if (ret) {
+			clk_disable(info->clk);
+			dev_err(info->dev,
+				"failed enabling sclk_adc clock: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
 static void exynos_adc_v1_init_hw(struct exynos_adc *info)
 {
 	u32 con1;
@@ -208,6 +273,16 @@ static const struct exynos_adc_data exynos_adc_v2_data = {
 	.start_conv	= exynos_adc_v2_start_conv,
 };
 
+static const struct exynos_adc_data exynos3250_adc_data = {
+	.num_channels	= MAX_EXYNOS3250_ADC_CHANNELS,
+	.needs_sclk	= true,
+
+	.init_hw	= exynos_adc_v2_init_hw,
+	.exit_hw	= exynos_adc_v2_exit_hw,
+	.clear_irq	= exynos_adc_v2_clear_irq,
+	.start_conv	= exynos_adc_v2_start_conv,
+};
+
 static const struct of_device_id exynos_adc_match[] = {
 	{
 		.compatible = "samsung,exynos-adc-v1",
@@ -215,6 +290,9 @@ static const struct of_device_id exynos_adc_match[] = {
 	}, {
 		.compatible = "samsung,exynos-adc-v2",
 		.data = &exynos_adc_v2_data,
+	}, {
+		.compatible = "samsung,exynos3250-adc",
+		.data = &exynos3250_adc_data,
 	},
 	{},
 };
@@ -376,6 +454,7 @@ static int exynos_adc_probe(struct platform_device *pdev)
 	}
 
 	info->irq = irq;
+	info->dev = &pdev->dev;
 
 	init_completion(&info->completion);
 
@@ -386,6 +465,16 @@ static int exynos_adc_probe(struct platform_device *pdev)
 		return PTR_ERR(info->clk);
 	}
 
+	if (info->data->needs_sclk) {
+		info->sclk = devm_clk_get(&pdev->dev, "sclk");
+		if (IS_ERR(info->sclk)) {
+			dev_err(&pdev->dev,
+				"failed getting sclk clock, err = %ld\n",
+				PTR_ERR(info->sclk));
+			return PTR_ERR(info->sclk);
+		}
+	}
+
 	info->vdd = devm_regulator_get(&pdev->dev, "vdd");
 	if (IS_ERR(info->vdd)) {
 		dev_err(&pdev->dev, "failed getting regulator, err = %ld\n",
@@ -397,10 +486,14 @@ static int exynos_adc_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	ret = clk_prepare_enable(info->clk);
+	ret = exynos_adc_prepare_clk(info);
 	if (ret)
 		goto err_disable_reg;
 
+	ret = exynos_adc_enable_clk(info);
+	if (ret)
+		goto err_unprepare_clk;
+
 	platform_set_drvdata(pdev, indio_dev);
 
 	indio_dev->name = dev_name(&pdev->dev);
@@ -443,7 +536,9 @@ err_irq:
 err_disable_clk:
 	if (info->data->exit_hw)
 		info->data->exit_hw(info);
-	clk_disable_unprepare(info->clk);
+	exynos_adc_disable_clk(info);
+err_unprepare_clk:
+	exynos_adc_unprepare_clk(info);
 err_disable_reg:
 	regulator_disable(info->vdd);
 	return ret;
@@ -460,7 +555,8 @@ static int exynos_adc_remove(struct platform_device *pdev)
 	free_irq(info->irq, info);
 	if (info->data->exit_hw)
 		info->data->exit_hw(info);
-	clk_disable_unprepare(info->clk);
+	exynos_adc_disable_clk(info);
+	exynos_adc_unprepare_clk(info);
 	regulator_disable(info->vdd);
 
 	return 0;
@@ -474,8 +570,7 @@ static int exynos_adc_suspend(struct device *dev)
 
 	if (info->data->exit_hw)
 		info->data->exit_hw(info);
-
-	clk_disable_unprepare(info->clk);
+	exynos_adc_disable_clk(info);
 	regulator_disable(info->vdd);
 
 	return 0;
@@ -491,7 +586,7 @@ static int exynos_adc_resume(struct device *dev)
 	if (ret)
 		return ret;
 
-	ret = clk_prepare_enable(info->clk);
+	ret = exynos_adc_enable_clk(info);
 	if (ret)
 		return ret;