[media] rc: sunxi-cir: Add support for an optional reset controller

On sun6i the cir block is attached to the reset controller, add support
for de-asserting the reset if a reset controller is specified in dt.

Signed-off-by: Hans de Goede <[e-mail]>
Acked-by: Mauro Carvalho Chehab <[e-mail]>
Acked-by: Maxime Ripard <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/devicetree/bindings/media/sunxi-ir.txt

···
 
 Optional properties:
 - linux,rc-map-name : Remote control map name.
+- resets : phandle + reset specifier pair
 
 Example:
 
···
 	compatible = "allwinner,sun4i-a10-ir";
 	clocks = <&apb0_gates 6>, <&ir0_clk>;
 	clock-names = "apb", "ir";
+	resets = <&apb0_rst 1>;
 	interrupts = <0 5 1>;
 	reg = <0x01C21800 0x40>;
 	linux,rc-map-name = "rc-rc6-mce";

drivers/media/rc/sunxi-cir.c

···
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/of_platform.h>
+#include <linux/reset.h>
 #include <media/rc-core.h>
 
 #define SUNXI_IR_DEV "sunxi-ir"
···
 	int             irq;
 	struct clk      *clk;
 	struct clk      *apb_clk;
+	struct reset_control *rst;
 	const char      *map_name;
 };
 
···
 		return PTR_ERR(ir->clk);
 	}
 
+	/* Reset (optional) */
+	ir->rst = devm_reset_control_get_optional(dev, NULL);
+	if (IS_ERR(ir->rst)) {
+		ret = PTR_ERR(ir->rst);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+		ir->rst = NULL;
+	} else {
+		ret = reset_control_deassert(ir->rst);
+		if (ret)
+			return ret;
+	}
+
 	ret = clk_set_rate(ir->clk, SUNXI_IR_BASE_CLK);
 	if (ret) {
 		dev_err(dev, "set ir base clock failed!\n");
-		return ret;
+		goto exit_reset_assert;
 	}
 
 	if (clk_prepare_enable(ir->apb_clk)) {
 		dev_err(dev, "try to enable apb_ir_clk failed\n");
-		return -EINVAL;
+		ret = -EINVAL;
+		goto exit_reset_assert;
 	}
 
 	if (clk_prepare_enable(ir->clk)) {
···
 	clk_disable_unprepare(ir->clk);
 exit_clkdisable_apb_clk:
 	clk_disable_unprepare(ir->apb_clk);
+exit_reset_assert:
+	if (ir->rst)
+		reset_control_assert(ir->rst);
 
 	return ret;
 }
···
 
 	clk_disable_unprepare(ir->clk);
 	clk_disable_unprepare(ir->apb_clk);
+	if (ir->rst)
+		reset_control_assert(ir->rst);
 
 	spin_lock_irqsave(&ir->ir_lock, flags);
 	/* disable IR IRQ */