iio: adc: rockchip_saradc: add support for rk3066-tsadc variant

Older Rockchip SoCs, at least the rk3066, used a slightly modified saradc
for temperature measurements. This so called tsadc does not contain any
active parts like temperature interrupts and only supports polling the
current temperature. The returned voltage can then be converted by a
suitable thermal driver to and actual temperature and used for thermal
handling.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt

 Rockchip Successive Approximation Register (SAR) A/D Converter bindings
 
 Required properties:
-- compatible: Should be "rockchip,saradc"
+- compatible: Should be "rockchip,saradc" or "rockchip,rk3066-tsadc"
 - reg: physical base address of the controller and length of memory mapped
        region.
 - interrupts: The interrupt number to the cpu. The interrupt specifier format

drivers/iio/adc/rockchip_saradc.c

@@ -18,13 +18,13 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/regulator/consumer.h>
 #include <linux/iio/iio.h>
 
 #define SARADC_DATA			0x00
-#define SARADC_DATA_MASK		0x3ff
 
 #define SARADC_STAS			0x04
 #define SARADC_STAS_BUSY		BIT(0)
@@ -38,15 +38,22 @@
 #define SARADC_DLY_PU_SOC		0x0c
 #define SARADC_DLY_PU_SOC_MASK		0x3f
 
-#define SARADC_BITS			10
 #define SARADC_TIMEOUT			msecs_to_jiffies(100)
 
+struct rockchip_saradc_data {
+	int				num_bits;
+	const struct iio_chan_spec	*channels;
+	int				num_channels;
+	unsigned long			clk_rate;
+};
+
 struct rockchip_saradc {
 	void __iomem		*regs;
 	struct clk		*pclk;
 	struct clk		*clk;
 	struct completion	completion;
 	struct regulator	*vref;
+	const struct rockchip_saradc_data *data;
 	u16			last_val;
 };
 
@@ -90,7 +97,7 @@ static int rockchip_saradc_read_raw(struct iio_dev *indio_dev,
 		}
 
 		*val = ret / 1000;
-		*val2 = SARADC_BITS;
+		*val2 = info->data->num_bits;
 		return IIO_VAL_FRACTIONAL_LOG2;
 	default:
 		return -EINVAL;
@@ -103,7 +110,7 @@ static irqreturn_t rockchip_saradc_isr(int irq, void *dev_id)
 
 	/* Read value */
 	info->last_val = readl_relaxed(info->regs + SARADC_DATA);
-	info->last_val &= SARADC_DATA_MASK;
+	info->last_val &= GENMASK(info->data->num_bits - 1, 0);
 
 	/* Clear irq & power down adc */
 	writel_relaxed(0, info->regs + SARADC_CTRL);
@@ -133,12 +140,44 @@ static const struct iio_chan_spec rockchip_saradc_iio_channels[] = {
 	ADC_CHANNEL(2, "adc2"),
 };
 
+static const struct rockchip_saradc_data saradc_data = {
+	.num_bits = 10,
+	.channels = rockchip_saradc_iio_channels,
+	.num_channels = ARRAY_SIZE(rockchip_saradc_iio_channels),
+	.clk_rate = 1000000,
+};
+
+static const struct iio_chan_spec rockchip_rk3066_tsadc_iio_channels[] = {
+	ADC_CHANNEL(0, "adc0"),
+	ADC_CHANNEL(1, "adc1"),
+};
+
+static const struct rockchip_saradc_data rk3066_tsadc_data = {
+	.num_bits = 12,
+	.channels = rockchip_rk3066_tsadc_iio_channels,
+	.num_channels = ARRAY_SIZE(rockchip_rk3066_tsadc_iio_channels),
+	.clk_rate = 50000,
+};
+
+static const struct of_device_id rockchip_saradc_match[] = {
+	{
+		.compatible = "rockchip,saradc",
+		.data = &saradc_data,
+	}, {
+		.compatible = "rockchip,rk3066-tsadc",
+		.data = &rk3066_tsadc_data,
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, rockchip_saradc_match);
+
 static int rockchip_saradc_probe(struct platform_device *pdev)
 {
 	struct rockchip_saradc *info = NULL;
 	struct device_node *np = pdev->dev.of_node;
 	struct iio_dev *indio_dev = NULL;
 	struct resource	*mem;
+	const struct of_device_id *match;
 	int ret;
 	int irq;
 
@@ -152,6 +191,9 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
 	}
 	info = iio_priv(indio_dev);
 
+	match = of_match_device(rockchip_saradc_match, &pdev->dev);
+	info->data = match->data;
+
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	info->regs = devm_ioremap_resource(&pdev->dev, mem);
 	if (IS_ERR(info->regs))
@@ -192,10 +234,10 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
 	}
 
 	/*
-	 * Use a default of 1MHz for the converter clock.
+	 * Use a default value for the converter clock.
 	 * This may become user-configurable in the future.
 	 */
-	ret = clk_set_rate(info->clk, 1000000);
+	ret = clk_set_rate(info->clk, info->data->clk_rate);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to set adc clk rate, %d\n", ret);
 		return ret;
@@ -227,8 +269,8 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
 	indio_dev->info = &rockchip_saradc_iio_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
-	indio_dev->channels = rockchip_saradc_iio_channels;
-	indio_dev->num_channels = ARRAY_SIZE(rockchip_saradc_iio_channels);
+	indio_dev->channels = info->data->channels;
+	indio_dev->num_channels = info->data->num_channels;
 
 	ret = iio_device_register(indio_dev);
 	if (ret)
@@ -296,12 +338,6 @@ static int rockchip_saradc_resume(struct device *dev)
 static SIMPLE_DEV_PM_OPS(rockchip_saradc_pm_ops,
 			 rockchip_saradc_suspend, rockchip_saradc_resume);
 
-static const struct of_device_id rockchip_saradc_match[] = {
-	{ .compatible = "rockchip,saradc" },
-	{},
-};
-MODULE_DEVICE_TABLE(of, rockchip_saradc_match);
-
 static struct platform_driver rockchip_saradc_driver = {
 	.probe		= rockchip_saradc_probe,
 	.remove		= rockchip_saradc_remove,