mfd: atmel-hlcdc: Implement config synchronization

Some HLCDC registers cannot be written until the hardware has finished
applying the previous configuration request. If they are written while
an action is still in progress, the new configuration might be silently
ignored, resulting in unpredictable behavior.

Hide the config synchronization stuff in a regmap implementation and use
this implementation instead of the generic mmio one.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/atmel-hlcdc.c

@@ -18,6 +18,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/iopoll.h>
 #include <linux/mfd/atmel-hlcdc.h>
 #include <linux/mfd/core.h>
 #include <linux/module.h>
@@ -26,6 +27,10 @@
 
 #define ATMEL_HLCDC_REG_MAX		(0x4000 - 0x4)
 
+struct atmel_hlcdc_regmap {
+	void __iomem *regs;
+};
+
 static const struct mfd_cell atmel_hlcdc_cells[] = {
 	{
 		.name = "atmel-hlcdc-pwm",
@@ -37,28 +42,62 @@ static const struct mfd_cell atmel_hlcdc_cells[] = {
 	},
 };
 
+static int regmap_atmel_hlcdc_reg_write(void *context, unsigned int reg,
+					unsigned int val)
+{
+	struct atmel_hlcdc_regmap *hregmap = context;
+
+	if (reg <= ATMEL_HLCDC_DIS) {
+		u32 status;
+
+		readl_poll_timeout(hregmap->regs + ATMEL_HLCDC_SR, status,
+				   !(status & ATMEL_HLCDC_SIP), 1, 100);
+	}
+
+	writel(val, hregmap->regs + reg);
+
+	return 0;
+}
+
+static int regmap_atmel_hlcdc_reg_read(void *context, unsigned int reg,
+				       unsigned int *val)
+{
+	struct atmel_hlcdc_regmap *hregmap = context;
+
+	*val = readl(hregmap->regs + reg);
+
+	return 0;
+}
+
 static const struct regmap_config atmel_hlcdc_regmap_config = {
 	.reg_bits = 32,
 	.val_bits = 32,
 	.reg_stride = 4,
 	.max_register = ATMEL_HLCDC_REG_MAX,
+	.reg_write = regmap_atmel_hlcdc_reg_write,
+	.reg_read = regmap_atmel_hlcdc_reg_read,
+	.fast_io = true,
 };
 
 static int atmel_hlcdc_probe(struct platform_device *pdev)
 {
+	struct atmel_hlcdc_regmap *hregmap;
 	struct device *dev = &pdev->dev;
 	struct atmel_hlcdc *hlcdc;
 	struct resource *res;
-	void __iomem *regs;
+
+	hregmap = devm_kzalloc(dev, sizeof(*hregmap), GFP_KERNEL);
+	if (!hregmap)
+		return -ENOMEM;
 
 	hlcdc = devm_kzalloc(dev, sizeof(*hlcdc), GFP_KERNEL);
 	if (!hlcdc)
 		return -ENOMEM;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	regs = devm_ioremap_resource(dev, res);
-	if (IS_ERR(regs))
-		return PTR_ERR(regs);
+	hregmap->regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(hregmap->regs))
+		return PTR_ERR(hregmap->regs);
 
 	hlcdc->irq = platform_get_irq(pdev, 0);
 	if (hlcdc->irq < 0)
@@ -82,7 +121,7 @@ static int atmel_hlcdc_probe(struct platform_device *pdev)
 		return PTR_ERR(hlcdc->slow_clk);
 	}
 
-	hlcdc->regmap = devm_regmap_init_mmio(dev, regs,
+	hlcdc->regmap = devm_regmap_init(dev, NULL, hregmap,
 					 &atmel_hlcdc_regmap_config);
 	if (IS_ERR(hlcdc->regmap))
 		return PTR_ERR(hlcdc->regmap);