pwm: mediatek: add pwm support for MediaTek MT7987 SoC

This patch adds pwm support for MediaTek MT7987 SoC.

diff --git a/arch/arm/dts/mt7987-pinctrl.dtsi b/arch/arm/dts/mt7987-pinctrl.dtsi
index b5e643f..dfde212 100644
--- a/arch/arm/dts/mt7987-pinctrl.dtsi
+++ b/arch/arm/dts/mt7987-pinctrl.dtsi
@@ -191,6 +191,20 @@
 		};
 	};
 
+	pwm_pins: pwm-pins {
+		mux {
+			/*
+			 * - pwm0   : PWM0@PIN13
+			 * - pwm1_0 : PWM1@PIN7  (share with JTAG)
+			 *   pwm1_1 : PWM1@PIN43 (share with i2c0)
+			 * - pwm2_0 : PWM2@PIN12 (share with PCM)
+			 *   pwm2_1 : PWM2@PIN44 (share with i2c0)
+			 */
+			function = "pwm";
+			groups = "pwm0";
+		};
+	};
+
 	uart1_pins: uart1-pins {
 		mux {
 			function = "uart";
diff --git a/arch/arm/dts/mt7987.dtsi b/arch/arm/dts/mt7987.dtsi
index fd1585f..4c1d597 100644
--- a/arch/arm/dts/mt7987.dtsi
+++ b/arch/arm/dts/mt7987.dtsi
@@ -389,21 +389,15 @@
 		};
 
 		pwm: pwm@10048000 {
-			compatible = "mediatek,mt7988-pwm";
+			compatible = "mediatek,mt7987-pwm";
 			reg = <0 0x10048000 0 0x1000>;
 			#pwm-cells = <2>;
 			clocks = <&infracfg CLK_INFRA_66M_PWM_BCK>,
 				 <&infracfg CLK_INFRA_66M_PWM_HCK>,
-				 <&clkxtal>,
-				 <&clkxtal>,
-				 <&clkxtal>,
-				 <&clkxtal>,
-				 <&clkxtal>,
-				 <&clkxtal>,
-				 <&clkxtal>,
-				 <&clkxtal>;
-			clock-names = "top", "main", "pwm1", "pwm2", "pwm3",
-				      "pwm4","pwm5","pwm6","pwm7","pwm8";
+				 <&infracfg CLK_INFRA_66M_PWM_HCK>,
+				 <&infracfg CLK_INFRA_66M_PWM_HCK>,
+				 <&infracfg CLK_INFRA_66M_PWM_HCK>;
+			clock-names = "top", "main", "pwm1", "pwm2", "pwm3";
 			status = "disabled";
 		};
 
diff --git a/arch/arm/dts/mt7987a.dtsi b/arch/arm/dts/mt7987a.dtsi
index 028f563..bf53e89 100644
--- a/arch/arm/dts/mt7987a.dtsi
+++ b/arch/arm/dts/mt7987a.dtsi
@@ -59,6 +59,8 @@
 };
 
 &pwm {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pwm_pins>;
 	status = "okay";
 };
 
diff --git a/drivers/pwm/pwm-mtk.c b/drivers/pwm/pwm-mtk.c
index 5cf2eba..898e353 100644
--- a/drivers/pwm/pwm-mtk.c
+++ b/drivers/pwm/pwm-mtk.c
@@ -30,6 +30,7 @@
 enum mtk_pwm_reg_ver {
 	PWM_REG_V1,
 	PWM_REG_V2,
+	PWM_REG_V3,
 };
 
 static const unsigned int mtk_pwm_reg_offset_v1[] = {
@@ -40,6 +41,10 @@
 	0x0080, 0x00c0, 0x0100, 0x0140, 0x0180, 0x01c0, 0x0200, 0x0240
 };
 
+static const unsigned int mtk_pwm_reg_offset_v3[] = {
+	0x0100, 0x0200, 0x0300, 0x0400, 0x0500, 0x600, 0x700, 0x0800
+};
+
 struct mtk_pwm_soc {
 	unsigned int num_pwms;
 	bool pwm45_fixup;
@@ -60,6 +65,10 @@
 	u32 offset;
 
 	switch (priv->soc->reg_ver) {
+	case PWM_REG_V3:
+		offset = mtk_pwm_reg_offset_v3[channel];
+		break;
+
 	case PWM_REG_V2:
 		offset = mtk_pwm_reg_offset_v2[channel];
 		break;
@@ -203,6 +212,12 @@
 	.reg_ver = PWM_REG_V1,
 };
 
+static const struct mtk_pwm_soc mt7987_data = {
+	.num_pwms = 3,
+	.pwm45_fixup = false,
+	.reg_ver = PWM_REG_V3,
+};
+
 static const struct mtk_pwm_soc mt7988_data = {
 	.num_pwms = 8,
 	.pwm45_fixup = false,
@@ -215,6 +230,7 @@
 	{ .compatible = "mediatek,mt7629-pwm", .data = (ulong)&mt7629_data },
 	{ .compatible = "mediatek,mt7981-pwm", .data = (ulong)&mt7981_data },
 	{ .compatible = "mediatek,mt7986-pwm", .data = (ulong)&mt7986_data },
+	{ .compatible = "mediatek,mt7987-pwm", .data = (ulong)&mt7987_data },
 	{ .compatible = "mediatek,mt7988-pwm", .data = (ulong)&mt7988_data },
 	{ }
 };