serial: vt8500: UART uses gated clock rather than 24Mhz reference

UART modules on Wondermedia SoCs are connected via a gated clock
source, rather than directly to the 24Mhz reference clock. While
uboot enables UART0 for debugging, other UART ports are unavailable
until the clock is enabled.

This patch checks that a valid clock is actually passed from devicetree,
enables the clock in probe. This change removes the fallback when a
clock was not specified as it doesn't apply any longer (and would only
work if the UART clock was already enabled).

DTSI files are updated for VT8500, WM8505 and WM8650.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 127 insertions, 27 deletions

diff --git a/arch/arm/boot/dts/vt8500.dtsi b/arch/arm/boot/dts/vt8500.dtsi
index d8645e990b21..cf31ced46602 100644
--- a/arch/arm/boot/dts/vt8500.dtsi
+++ b/arch/arm/boot/dts/vt8500.dtsi
@@ -45,6 +45,38 @@
 					compatible = "fixed-clock";
 					clock-frequency = <24000000>;
 				};
+
+				clkuart0: uart0 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <1>;
+				};
+
+				clkuart1: uart1 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <2>;
+				};
+
+				clkuart2: uart2 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <3>;
+				};
+
+				clkuart3: uart3 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <4>;
+				};
 			};
 		};
 
@@ -83,28 +115,28 @@
 			compatible = "via,vt8500-uart";
 			reg = <0xd8200000 0x1040>;
 			interrupts = <32>;
-			clocks = <&ref24>;
+			clocks = <&clkuart0>;
 		};
 
 		uart@d82b0000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd82b0000 0x1040>;
 			interrupts = <33>;
-			clocks = <&ref24>;
+			clocks = <&clkuart1>;
 		};
 
 		uart@d8210000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd8210000 0x1040>;
 			interrupts = <47>;
-			clocks = <&ref24>;
+			clocks = <&clkuart2>;
 		};
 
 		uart@d82c0000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd82c0000 0x1040>;
 			interrupts = <50>;
-			clocks = <&ref24>;
+			clocks = <&clkuart3>;
 		};
 
 		rtc@d8100000 {
diff --git a/arch/arm/boot/dts/wm8505.dtsi b/arch/arm/boot/dts/wm8505.dtsi
index 330f833ac3b0..e74a1c0fb9a2 100644
--- a/arch/arm/boot/dts/wm8505.dtsi
+++ b/arch/arm/boot/dts/wm8505.dtsi
@@ -59,6 +59,54 @@
 					compatible = "fixed-clock";
 					clock-frequency = <24000000>;
 				};
+
+				clkuart0: uart0 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <1>;
+				};
+
+				clkuart1: uart1 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <2>;
+				};
+
+				clkuart2: uart2 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <3>;
+				};
+
+				clkuart3: uart3 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <4>;
+				};
+
+				clkuart4: uart4 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <22>;
+				};
+
+				clkuart5: uart5 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <23>;
+				};
 			};
 		};
 
@@ -96,42 +144,42 @@
 			compatible = "via,vt8500-uart";
 			reg = <0xd8200000 0x1040>;
 			interrupts = <32>;
-			clocks = <&ref24>;
+			clocks = <&clkuart0>;
 		};
 
 		uart@d82b0000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd82b0000 0x1040>;
 			interrupts = <33>;
-			clocks = <&ref24>;
+			clocks = <&clkuart1>;
 		};
 
 		uart@d8210000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd8210000 0x1040>;
 			interrupts = <47>;
-			clocks = <&ref24>;
+			clocks = <&clkuart2>;
 		};
 
 		uart@d82c0000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd82c0000 0x1040>;
 			interrupts = <50>;
-			clocks = <&ref24>;
+			clocks = <&clkuart3>;
 		};
 
 		uart@d8370000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd8370000 0x1040>;
 			interrupts = <31>;
-			clocks = <&ref24>;
+			clocks = <&clkuart4>;
 		};
 
 		uart@d8380000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd8380000 0x1040>;
 			interrupts = <30>;
-			clocks = <&ref24>;
+			clocks = <&clkuart5>;
 		};
 
 		rtc@d8100000 {
diff --git a/arch/arm/boot/dts/wm8650.dtsi b/arch/arm/boot/dts/wm8650.dtsi
index 83b9467559bb..db3c0a12e052 100644
--- a/arch/arm/boot/dts/wm8650.dtsi
+++ b/arch/arm/boot/dts/wm8650.dtsi
@@ -75,6 +75,22 @@
 					reg = <0x204>;
 				};
 
+				clkuart0: uart0 {
+ 					#clock-cells = <0>;
+ 					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <1>;
+ 				};
+
+				clkuart1: uart1 {
+					#clock-cells = <0>;
+					compatible = "via,vt8500-device-clock";
+					clocks = <&ref24>;
+					enable-reg = <0x250>;
+					enable-bit = <2>;
+				};
+
 				arm: arm {
 					#clock-cells = <0>;
 					compatible = "via,vt8500-device-clock";
@@ -128,14 +144,14 @@
 			compatible = "via,vt8500-uart";
 			reg = <0xd8200000 0x1040>;
 			interrupts = <32>;
-			clocks = <&ref24>;
+			clocks = <&clkuart0>;
 		};
 
 		uart@d82b0000 {
 			compatible = "via,vt8500-uart";
 			reg = <0xd82b0000 0x1040>;
 			interrupts = <33>;
-			clocks = <&ref24>;
+			clocks = <&clkuart1>;
 		};
 
 		rtc@d8100000 {
diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
index ff391db0a220..798bf944a2e5 100644
--- a/drivers/tty/serial/vt8500_serial.c
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -584,6 +584,23 @@ static int vt8500_serial_probe(struct platform_device *pdev)
 	if (!vt8500_port)
 		return -ENOMEM;
 
+	vt8500_port->uart.membase = devm_request_and_ioremap(&pdev->dev, mmres);
+	if (!vt8500_port->uart.membase)
+		return -EADDRNOTAVAIL;
+
+	vt8500_port->clk = of_clk_get(pdev->dev.of_node, 0);
+	if (IS_ERR(vt8500_port->clk)) {
+		dev_err(&pdev->dev, "failed to get clock\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	ret = clk_prepare_enable(vt8500_port->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable clock\n");
+		goto err;
+	}
+
 	vt8500_port->uart.type = PORT_VT8500;
 	vt8500_port->uart.iotype = UPIO_MEM;
 	vt8500_port->uart.mapbase = mmres->start;
@@ -593,25 +610,11 @@ static int vt8500_serial_probe(struct platform_device *pdev)
 	vt8500_port->uart.line = port;
 	vt8500_port->uart.dev = &pdev->dev;
 	vt8500_port->uart.flags = UPF_IOREMAP | UPF_BOOT_AUTOCONF;
-
-	vt8500_port->clk = of_clk_get(pdev->dev.of_node, 0);
-	if (vt8500_port->clk) {
-		vt8500_port->uart.uartclk = clk_get_rate(vt8500_port->clk);
-	} else {
-		/* use the default of 24Mhz if not specified and warn */
-		pr_warn("%s: serial clock source not specified\n", __func__);
-		vt8500_port->uart.uartclk = 24000000;
-	}
+	vt8500_port->uart.uartclk = clk_get_rate(vt8500_port->clk);
 
 	snprintf(vt8500_port->name, sizeof(vt8500_port->name),
 		 "VT8500 UART%d", pdev->id);
 
-	vt8500_port->uart.membase = devm_request_and_ioremap(&pdev->dev, mmres);
-	if (!vt8500_port->uart.membase) {
-		ret = -EADDRNOTAVAIL;
-		goto err;
-	}
-
 	vt8500_uart_ports[port] = vt8500_port;
 
 	uart_add_one_port(&vt8500_uart_driver, &vt8500_port->uart);
@@ -630,6 +633,7 @@ static int vt8500_serial_remove(struct platform_device *pdev)
 	struct vt8500_port *vt8500_port = platform_get_drvdata(pdev);
 
 	platform_set_drvdata(pdev, NULL);
+	clk_disable_unprepare(vt8500_port->clk);
 	uart_remove_one_port(&vt8500_uart_driver, &vt8500_port->uart);
 	kfree(vt8500_port);