pwm: mediatek: Add MT7628 support

Add support for MT7628. The SoC is legacy MIPS and hence has no complex
clock tree. This patch add an extra flag to the SoC specific data
indicating, that no clocks are present.
Signed-off-by: John Crispin <john@phrozen.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/Kconfig

@@ -286,7 +286,7 @@ config PWM_MTK_DISP
 
 config PWM_MEDIATEK
 	tristate "MediaTek PWM support"
-	depends on ARCH_MEDIATEK || COMPILE_TEST
+	depends on ARCH_MEDIATEK || RALINK || COMPILE_TEST
 	help
 	  Generic PWM framework driver for Mediatek ARM SoC.
 

drivers/pwm/pwm-mediatek.c

@@ -57,6 +57,7 @@ static const char * const mtk_pwm_clk_name[MTK_CLK_MAX] = {
 struct mtk_pwm_platform_data {
 	unsigned int num_pwms;
 	bool pwm45_fixup;
+	bool has_clks;
 };
 
 /**
@@ -86,6 +87,9 @@ static int mtk_pwm_clk_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	struct mtk_pwm_chip *pc = to_mtk_pwm_chip(chip);
 	int ret;
 
+	if (!pc->soc->has_clks)
+		return 0;
+
 	ret = clk_prepare_enable(pc->clks[MTK_CLK_TOP]);
 	if (ret < 0)
 		return ret;
@@ -112,6 +116,9 @@ static void mtk_pwm_clk_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct mtk_pwm_chip *pc = to_mtk_pwm_chip(chip);
 
+	if (!pc->soc->has_clks)
+		return;
+
 	clk_disable_unprepare(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
 	clk_disable_unprepare(pc->clks[MTK_CLK_MAIN]);
 	clk_disable_unprepare(pc->clks[MTK_CLK_TOP]);
@@ -239,7 +246,7 @@ static int mtk_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(pc->regs))
 		return PTR_ERR(pc->regs);
 
-	for (i = 0; i < data->num_pwms + 2; i++) {
+	for (i = 0; i < data->num_pwms + 2 && pc->soc->has_clks; i++) {
 		pc->clks[i] = devm_clk_get(&pdev->dev, mtk_pwm_clk_name[i]);
 		if (IS_ERR(pc->clks[i])) {
 			dev_err(&pdev->dev, "clock: %s fail: %ld\n",
@@ -274,22 +281,32 @@ static int mtk_pwm_remove(struct platform_device *pdev)
 static const struct mtk_pwm_platform_data mt2712_pwm_data = {
 	.num_pwms = 8,
 	.pwm45_fixup = false,
+	.has_clks = true,
 };
 
 static const struct mtk_pwm_platform_data mt7622_pwm_data = {
 	.num_pwms = 6,
 	.pwm45_fixup = false,
+	.has_clks = true,
 };
 
 static const struct mtk_pwm_platform_data mt7623_pwm_data = {
 	.num_pwms = 5,
 	.pwm45_fixup = true,
+	.has_clks = true,
+};
+
+static const struct mtk_pwm_platform_data mt7628_pwm_data = {
+	.num_pwms = 4,
+	.pwm45_fixup = true,
+	.has_clks = false,
 };
 
 static const struct of_device_id mtk_pwm_of_match[] = {
 	{ .compatible = "mediatek,mt2712-pwm", .data = &mt2712_pwm_data },
 	{ .compatible = "mediatek,mt7622-pwm", .data = &mt7622_pwm_data },
 	{ .compatible = "mediatek,mt7623-pwm", .data = &mt7623_pwm_data },
+	{ .compatible = "mediatek,mt7628-pwm", .data = &mt7628_pwm_data },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, mtk_pwm_of_match);