Input: bcm_iproc_tsc - use syscon to access shared registers

In Cygnus SOC touch screen controller registers are shared with ADC and
flex timer. Using readl/writel could lead to race condition. So touch
screen driver is enhanced to support register access using syscon framework
API's to take care of mutually exclusive access.

Signed-off-by: Raveendra Padasalagi <[e-mail]>
Reviewed-by: Ray Jui <[e-mail]>
Reviewed-by: Scott Branden <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Acked-by: Florian Fainelli <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt

···
 
 Required properties:
 - compatible: must be "brcm,iproc-touchscreen"
-- reg: physical base address of the controller and length of memory mapped
-  region.
+- ts_syscon: handler of syscon node defining physical base
+  address of the controller and length of memory mapped region.
+  If this property is selected please make sure MFD_SYSCON config
+  is enabled in the defconfig file.
 - clocks:  The clock provided by the SOC to driver the tsc
 - clock-name:  name for the clock
 - interrupts: The touchscreen controller's interrupt
+- address-cells: Specify the number of u32 entries needed in child nodes.
+  Should set to 1.
+- size-cells: Specify number of u32 entries needed to specify child nodes size
+  in reg property. Should set to 1.
 
 Optional properties:
 - scanning_period: Time between scans. Each step is 1024 us.  Valid 1-256.
···
 - touchscreen-inverted-x: X axis is inverted (boolean)
 - touchscreen-inverted-y: Y axis is inverted (boolean)
 
-Example:
+Example: An example of touchscreen node
 
-	touchscreen: tsc@0x180A6000 {
+	ts_adc_syscon: ts_adc_syscon@180a6000 {
+		compatible = "brcm,iproc-ts-adc-syscon","syscon";
+		reg = <0x180a6000 0xc30>;
+	};
+
+	touchscreen: touchscreen@180A6000 {
 		compatible = "brcm,iproc-touchscreen";
 		#address-cells = <1>;
 		#size-cells = <1>;
-		reg = <0x180A6000 0x40>;
+		ts_syscon = <&ts_adc_syscon>;
 		clocks = <&adc_clk>;
 		clock-names = "tsc_clk";
 		interrupts = <GIC_SPI 164 IRQ_TYPE_LEVEL_HIGH>;

arch/arm/boot/dts/bcm-cygnus.dtsi

···
 					<&pinctrl 142 10 1>;
 		};
 
-		touchscreen: tsc@180a6000 {
+		ts_adc_syscon: ts_adc_syscon@180a6000 {
+			compatible = "brcm,iproc-ts-adc-syscon", "syscon";
+			reg = <0x180a6000 0xc30>;
+		};
+
+		touchscreen: touchscreen@180a6000 {
 			compatible = "brcm,iproc-touchscreen";
-			reg = <0x180a6000 0x40>;
+			#address-cells = <1>;
+			#size-cells = <1>;
+			ts_syscon = <&ts_adc_syscon>;
 			clocks = <&asiu_clks BCM_CYGNUS_ASIU_ADC_CLK>;
 			clock-names = "tsc_clk";
 			interrupts = <GIC_SPI 164 IRQ_TYPE_LEVEL_HIGH>;

drivers/input/touchscreen/bcm_iproc_tsc.c

···
 #include <linux/io.h>
 #include <linux/clk.h>
 #include <linux/serio.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
 
 #define IPROC_TS_NAME "iproc-ts"
 
···
 #define TS_WIRE_MODE_BIT        BIT(1)
 
 #define dbg_reg(dev, priv, reg) \
-	dev_dbg(dev, "%20s= 0x%08x\n", #reg, readl((priv)->regs + reg))
+do { \
+	u32 val; \
+	regmap_read(priv->regmap, reg, &val); \
+	dev_dbg(dev, "%20s= 0x%08x\n", #reg, val); \
+} while (0)
 
 struct tsc_param {
 	/* Each step is 1024 us.  Valid 1-256 */
···
 	struct platform_device *pdev;
 	struct input_dev *idev;
 
-	void __iomem *regs;
+	struct regmap *regmap;
 	struct clk *tsc_clk;
 
 	int  pen_status;
···
 	int i;
 	bool needs_sync = false;
 
-	intr_status = readl(priv->regs + INTERRUPT_STATUS);
+	regmap_read(priv->regmap, INTERRUPT_STATUS, &intr_status);
 	intr_status &= TS_PEN_INTR_MASK | TS_FIFO_INTR_MASK;
 	if (intr_status == 0)
 		return IRQ_NONE;
 
 	/* Clear all interrupt status bits, write-1-clear */
-	writel(intr_status, priv->regs + INTERRUPT_STATUS);
-
+	regmap_write(priv->regmap, INTERRUPT_STATUS, intr_status);
 	/* Pen up/down */
 	if (intr_status & TS_PEN_INTR_MASK) {
-		if (readl(priv->regs + CONTROLLER_STATUS) & TS_PEN_DOWN)
+		regmap_read(priv->regmap, CONTROLLER_STATUS, &priv->pen_status);
+		if (priv->pen_status & TS_PEN_DOWN)
 			priv->pen_status = PEN_DOWN_STATUS;
 		else
 			priv->pen_status = PEN_UP_STATUS;
 
-		input_report_key(priv->idev, BTN_TOUCH, priv->pen_status);
+		input_report_key(priv->idev, BTN_TOUCH,	priv->pen_status);
 		needs_sync = true;
 
 		dev_dbg(&priv->pdev->dev,
···
 	/* coordinates in FIFO exceed the theshold */
 	if (intr_status & TS_FIFO_INTR_MASK) {
 		for (i = 0; i < priv->cfg_params.fifo_threshold; i++) {
-			raw_coordinate = readl(priv->regs + FIFO_DATA);
+			regmap_read(priv->regmap, FIFO_DATA, &raw_coordinate);
 			if (raw_coordinate == INVALID_COORD)
 				continue;
 
···
 			x = (x >> 4) & 0x0FFF;
 			y = (y >> 4) & 0x0FFF;
 
-			/* adjust x y according to lcd tsc mount angle */
+			/* Adjust x y according to LCD tsc mount angle. */
 			if (priv->cfg_params.invert_x)
 				x = priv->cfg_params.max_x - x;
 
···
 
 static int iproc_ts_start(struct input_dev *idev)
 {
-	struct iproc_ts_priv *priv = input_get_drvdata(idev);
 	u32 val;
+	u32 mask;
 	int error;
+	struct iproc_ts_priv *priv = input_get_drvdata(idev);
 
 	/* Enable clock */
 	error = clk_prepare_enable(priv->tsc_clk);
···
 	 *  FIFO reaches the int_th value, and pen event(up/down)
 	 */
 	val = TS_PEN_INTR_MASK | TS_FIFO_INTR_MASK;
-	writel(val, priv->regs + INTERRUPT_MASK);
+	regmap_update_bits(priv->regmap, INTERRUPT_MASK, val, val);
 
-	writel(priv->cfg_params.fifo_threshold, priv->regs + INTERRUPT_THRES);
+	val = priv->cfg_params.fifo_threshold;
+	regmap_write(priv->regmap, INTERRUPT_THRES, val);
 
 	/* Initialize control reg1 */
 	val = 0;
···
 	val |= priv->cfg_params.debounce_timeout << DEBOUNCE_TIMEOUT_SHIFT;
 	val |= priv->cfg_params.settling_timeout << SETTLING_TIMEOUT_SHIFT;
 	val |= priv->cfg_params.touch_timeout << TOUCH_TIMEOUT_SHIFT;
-	writel(val, priv->regs + REGCTL1);
+	regmap_write(priv->regmap, REGCTL1, val);
 
 	/* Try to clear all interrupt status */
-	val = readl(priv->regs + INTERRUPT_STATUS);
-	val |= TS_FIFO_INTR_MASK | TS_PEN_INTR_MASK;
-	writel(val, priv->regs + INTERRUPT_STATUS);
+	val = TS_FIFO_INTR_MASK | TS_PEN_INTR_MASK;
+	regmap_update_bits(priv->regmap, INTERRUPT_STATUS, val, val);
 
 	/* Initialize control reg2 */
-	val = readl(priv->regs + REGCTL2);
-	val |= TS_CONTROLLER_EN_BIT | TS_WIRE_MODE_BIT;
-
-	val &= ~TS_CONTROLLER_AVGDATA_MASK;
+	val = TS_CONTROLLER_EN_BIT | TS_WIRE_MODE_BIT;
 	val |= priv->cfg_params.average_data << TS_CONTROLLER_AVGDATA_SHIFT;
 
-	val &= ~(TS_CONTROLLER_PWR_LDO |	/* PWR up LDO */
+	mask = (TS_CONTROLLER_AVGDATA_MASK);
+	mask |= (TS_CONTROLLER_PWR_LDO |	/* PWR up LDO */
 		   TS_CONTROLLER_PWR_ADC |	/* PWR up ADC */
 		   TS_CONTROLLER_PWR_BGP |	/* PWR up BGP */
 		   TS_CONTROLLER_PWR_TS);	/* PWR up TS */
-
-	writel(val, priv->regs + REGCTL2);
+	mask |= val;
+	regmap_update_bits(priv->regmap, REGCTL2, mask, val);
 
 	ts_reg_dump(priv);
 
···
 	u32 val;
 	struct iproc_ts_priv *priv = input_get_drvdata(dev);
 
-	writel(0, priv->regs + INTERRUPT_MASK); /* Disable all interrupts */
+	/*
+	 * Disable FIFO int_th and pen event(up/down)Interrupts only
+	 * as the interrupt mask register is shared between ADC, TS and
+	 * flextimer.
+	 */
+	val = TS_PEN_INTR_MASK | TS_FIFO_INTR_MASK;
+	regmap_update_bits(priv->regmap, INTERRUPT_MASK, val, 0);
 
 	/* Only power down touch screen controller */
-	val = readl(priv->regs + REGCTL2);
-	val |= TS_CONTROLLER_PWR_TS;
-	writel(val, priv->regs + REGCTL2);
+	val = TS_CONTROLLER_PWR_TS;
+	regmap_update_bits(priv->regmap, REGCTL2, val, val);
 
 	clk_disable(priv->tsc_clk);
 }
···
 {
 	struct iproc_ts_priv *priv;
 	struct input_dev *idev;
-	struct resource *res;
 	int irq;
 	int error;
 
···
 	if (!priv)
 		return -ENOMEM;
 
-	/* touchscreen controller memory mapped regs */
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	priv->regs = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(priv->regs)) {
-		error = PTR_ERR(priv->regs);
-		dev_err(&pdev->dev, "unable to map I/O memory: %d\n", error);
+	/* touchscreen controller memory mapped regs via syscon*/
+	priv->regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+							"ts_syscon");
+	if (IS_ERR(priv->regmap)) {
+		error = PTR_ERR(priv->regmap);
+		dev_err(&pdev->dev, "unable to map I/O memory:%d\n", error);
 		return error;
 	}