reset: hi6220: Add support for AO reset controller

This is required to bring Mali450 gpu out of reset.

Cc: Peter Griffin <peter.griffin@linaro.org>
Cc: Enrico Weigelt <info@metux.net>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
[jstultz: Added comment, Fix void return build issue
Reported-by: kbuild test robot <lkp@intel.com>]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/reset/hisilicon/hi6220_reset.c

@@ -33,6 +33,7 @@
 enum hi6220_reset_ctrl_type {
 	PERIPHERAL,
 	MEDIA,
+	AO,
 };
 
 struct hi6220_reset_data {
@@ -92,6 +93,65 @@ static const struct reset_control_ops hi6220_media_reset_ops = {
 	.deassert = hi6220_media_deassert,
 };
 
+#define AO_SCTRL_SC_PW_CLKEN0     0x800
+#define AO_SCTRL_SC_PW_CLKDIS0    0x804
+
+#define AO_SCTRL_SC_PW_RSTEN0     0x810
+#define AO_SCTRL_SC_PW_RSTDIS0    0x814
+
+#define AO_SCTRL_SC_PW_ISOEN0     0x820
+#define AO_SCTRL_SC_PW_ISODIS0    0x824
+#define AO_MAX_INDEX              12
+
+static int hi6220_ao_assert(struct reset_controller_dev *rc_dev,
+			       unsigned long idx)
+{
+	struct hi6220_reset_data *data = to_reset_data(rc_dev);
+	struct regmap *regmap = data->regmap;
+	int ret;
+
+	ret = regmap_write(regmap, AO_SCTRL_SC_PW_RSTEN0, BIT(idx));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(regmap, AO_SCTRL_SC_PW_ISOEN0, BIT(idx));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(regmap, AO_SCTRL_SC_PW_CLKDIS0, BIT(idx));
+	return ret;
+}
+
+static int hi6220_ao_deassert(struct reset_controller_dev *rc_dev,
+				 unsigned long idx)
+{
+	struct hi6220_reset_data *data = to_reset_data(rc_dev);
+	struct regmap *regmap = data->regmap;
+	int ret;
+
+	/*
+	 * It was suggested to disable isolation before enabling
+	 * the clocks and deasserting reset, to avoid glitches.
+	 * But this order is preserved to keep it matching the
+	 * vendor code.
+	 */
+	ret = regmap_write(regmap, AO_SCTRL_SC_PW_RSTDIS0, BIT(idx));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(regmap, AO_SCTRL_SC_PW_ISODIS0, BIT(idx));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(regmap, AO_SCTRL_SC_PW_CLKEN0, BIT(idx));
+	return ret;
+}
+
+static const struct reset_control_ops hi6220_ao_reset_ops = {
+	.assert = hi6220_ao_assert,
+	.deassert = hi6220_ao_deassert,
+};
+
 static int hi6220_reset_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
@@ -117,9 +177,12 @@ static int hi6220_reset_probe(struct platform_device *pdev)
 	if (type == MEDIA) {
 		data->rc_dev.ops = &hi6220_media_reset_ops;
 		data->rc_dev.nr_resets = MEDIA_MAX_INDEX;
-	} else {
+	} else if (type == PERIPHERAL) {
 		data->rc_dev.ops = &hi6220_peripheral_reset_ops;
 		data->rc_dev.nr_resets = PERIPH_MAX_INDEX;
+	} else {
+		data->rc_dev.ops = &hi6220_ao_reset_ops;
+		data->rc_dev.nr_resets = AO_MAX_INDEX;
 	}
 
 	return reset_controller_register(&data->rc_dev);
@@ -134,6 +197,10 @@ static const struct of_device_id hi6220_reset_match[] = {
 		.compatible = "hisilicon,hi6220-mediactrl",
 		.data = (void *)MEDIA,
 	},
+	{
+		.compatible = "hisilicon,hi6220-aoctrl",
+		.data = (void *)AO,
+	},
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, hi6220_reset_match);