[PATCH v2 0/2] 8250 UART driver for NXP LPC18xx family

[PATCH v2 0/2] 8250 UART driver for NXP LPC18xx family

[Joachim Eastwood]

This patch set adds a serial port driver for the 8250-
based UART found on LPC18xx/43xx devices. The UART is
16550A compatible with additional features like RS485
support, synchronous mode, IrDA, and DMA.

Driver includes basic UART support, RS485 mode and
optional DMA support. Tested both DMA and non-DMA
mode on EA4357 Dev Kit successfully.

Changes since v1:
 - DMA support + doc update
 - Cleaned up probe function

DMA support for LPC18xx will be posted soonish.

Joachim Eastwood (2):
  serial: 8250: add LPC18xx/43xx UART driver
  doc: dt: add documentation for nxp,lpc1850-uart

 .../bindings/serial/nxp,lpc1850-uart.txt           |  28 +++
 drivers/tty/serial/8250/8250_lpc18xx.c             | 230 +++++++++++++++++++++
 drivers/tty/serial/8250/Kconfig                    |   8 +
 drivers/tty/serial/8250/Makefile                   |   1 +
 4 files changed, 267 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/nxp,lpc1850-uart.txt
 create mode 100644 drivers/tty/serial/8250/8250_lpc18xx.c

-- 
1.8.0

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[PATCH v2 1/2] serial: 8250: add LPC18xx/43xx UART driver

[Joachim Eastwood]

Serial port driver for the 8250-based UART found on LPC18xx/43xx
devices. The UART is 16550A compatible with additional features
like RS485 support, synchronous mode, IrDA, and DMA.

For now only basic UART and RS485 operation is supported.

Signed-off-by: Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/tty/serial/8250/8250_lpc18xx.c | 230 +++++++++++++++++++++++++++++++++
 drivers/tty/serial/8250/Kconfig        |   8 ++
 drivers/tty/serial/8250/Makefile       |   1 +
 3 files changed, 239 insertions(+)
 create mode 100644 drivers/tty/serial/8250/8250_lpc18xx.c

diff --git a/drivers/tty/serial/8250/8250_lpc18xx.c b/drivers/tty/serial/8250/8250_lpc18xx.c
new file mode 100644
index 000000000000..99cd478851ff
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_lpc18xx.c
@@ -0,0 +1,230 @@
+/*
+ * Serial port driver for NXP LPC18xx/43xx UART
+ *
+ * Copyright (C) 2015 Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
+ *
+ * Based on 8250_mtk.c:
+ * Copyright (c) 2014 MundoReader S.L.
+ * Matthias Brugger <matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include "8250.h"
+
+/* Additional LPC18xx/43xx 8250 registers and bits */
+#define LPC18XX_UART_RS485CTRL		(0x04c / sizeof(u32))
+#define  LPC18XX_UART_RS485CTRL_NMMEN	BIT(0)
+#define  LPC18XX_UART_RS485CTRL_DCTRL	BIT(4)
+#define  LPC18XX_UART_RS485CTRL_OINV	BIT(5)
+#define LPC18XX_UART_RS485DLY		(0x054 / sizeof(u32))
+#define LPC18XX_UART_RS485DLY_MAX	255
+
+struct lpc18xx_uart_data {
+	struct uart_8250_dma dma;
+	struct clk *clk_uart;
+	struct clk *clk_reg;
+	int line;
+};
+
+static int lpc18xx_rs485_config(struct uart_port *port,
+				struct serial_rs485 *rs485)
+{
+	struct uart_8250_port *up = up_to_u8250p(port);
+	u32 rs485_ctrl_reg = 0;
+	u32 rs485_dly_reg = 0;
+	unsigned baud_clk;
+
+	if (rs485->flags & SER_RS485_ENABLED)
+		memset(rs485->padding, 0, sizeof(rs485->padding));
+	else
+		memset(rs485, 0, sizeof(*rs485));
+
+	rs485->flags &= SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND |
+			SER_RS485_RTS_AFTER_SEND;
+
+	if (rs485->flags & SER_RS485_ENABLED) {
+		rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_NMMEN |
+				  LPC18XX_UART_RS485CTRL_DCTRL;
+
+		if (rs485->flags & SER_RS485_RTS_ON_SEND) {
+			rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_OINV;
+			rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
+		} else {
+			rs485->flags |= SER_RS485_RTS_AFTER_SEND;
+		}
+	}
+
+	if (rs485->delay_rts_after_send) {
+		baud_clk = port->uartclk / up->dl_read(up);
+		rs485_dly_reg = DIV_ROUND_UP(rs485->delay_rts_after_send
+						* baud_clk, MSEC_PER_SEC);
+
+		if (rs485_dly_reg > LPC18XX_UART_RS485DLY_MAX)
+			rs485_dly_reg = LPC18XX_UART_RS485DLY_MAX;
+
+		/* Calculate the resulting delay in ms */
+		rs485->delay_rts_after_send = (rs485_dly_reg * MSEC_PER_SEC)
+						/ baud_clk;
+	}
+
+	/* Delay RTS before send not supported */
+	rs485->delay_rts_before_send = 0;
+
+	serial_out(up, LPC18XX_UART_RS485CTRL, rs485_ctrl_reg);
+	serial_out(up, LPC18XX_UART_RS485DLY, rs485_dly_reg);
+
+	port->rs485 = *rs485;
+
+	return 0;
+}
+
+static void lpc18xx_uart_serial_out(struct uart_port *p, int offset, int value)
+{
+	/*
+	 * For DMA mode one must ensure that the UART_FCR_DMA_SELECT
+	 * bit is set when FIFO is enabled. Even if DMA is not used
+	 * setting this bit doesn't seem to affect anything.
+	 */
+	if (offset == UART_FCR && (value & UART_FCR_ENABLE_FIFO))
+		value |= UART_FCR_DMA_SELECT;
+
+	offset = offset << p->regshift;
+	writel(value, p->membase + offset);
+}
+
+static int lpc18xx_serial_probe(struct platform_device *pdev)
+{
+	struct lpc18xx_uart_data *data;
+	struct uart_8250_port uart;
+	struct resource *res;
+	int irq, ret;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "irq not found");
+		return irq;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "memory resource not found");
+		return -EINVAL;
+	}
+
+	memset(&uart, 0, sizeof(uart));
+
+	uart.port.membase = devm_ioremap(&pdev->dev, res->start,
+					 resource_size(res));
+	if (!uart.port.membase)
+		return -ENOMEM;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->clk_uart = devm_clk_get(&pdev->dev, "uartclk");
+	if (IS_ERR(data->clk_uart)) {
+		dev_err(&pdev->dev, "uart clock not found\n");
+		return PTR_ERR(data->clk_uart);
+	}
+
+	data->clk_reg = devm_clk_get(&pdev->dev, "reg");
+	if (IS_ERR(data->clk_reg)) {
+		dev_err(&pdev->dev, "reg clock not found\n");
+		return PTR_ERR(data->clk_reg);
+	}
+
+	ret = clk_prepare_enable(data->clk_reg);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to enable reg clock\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(data->clk_uart);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to enable uart clock\n");
+		goto dis_clk_reg;
+	}
+
+	ret = of_alias_get_id(pdev->dev.of_node, "serial");
+	if (ret >= 0)
+		uart.port.line = ret;
+
+	data->dma.rx_param = data;
+	data->dma.tx_param = data;
+
+	spin_lock_init(&uart.port.lock);
+	uart.port.dev = &pdev->dev;
+	uart.port.irq = irq;
+	uart.port.iotype = UPIO_MEM32;
+	uart.port.mapbase = res->start;
+	uart.port.regshift = 2;
+	uart.port.type = PORT_16550A;
+	uart.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE | UPF_SKIP_TEST;
+	uart.port.uartclk = clk_get_rate(data->clk_uart);
+	uart.port.private_data = data;
+	uart.port.rs485_config = lpc18xx_rs485_config;
+	uart.port.serial_out = lpc18xx_uart_serial_out;
+
+	uart.dma = &data->dma;
+	uart.dma->rxconf.src_maxburst = 1;
+	uart.dma->txconf.dst_maxburst = 1;
+
+	ret = serial8250_register_8250_port(&uart);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "unable to register 8250 port\n");
+		goto dis_uart_clk;
+	}
+
+	data->line = ret;
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+
+dis_uart_clk:
+	clk_disable_unprepare(data->clk_uart);
+dis_clk_reg:
+	clk_disable_unprepare(data->clk_reg);
+	return ret;
+}
+
+static int lpc18xx_serial_remove(struct platform_device *pdev)
+{
+	struct lpc18xx_uart_data *data = platform_get_drvdata(pdev);
+
+	serial8250_unregister_port(data->line);
+	clk_disable_unprepare(data->clk_uart);
+	clk_disable_unprepare(data->clk_reg);
+
+	return 0;
+}
+
+static const struct of_device_id lpc18xx_serial_match[] = {
+	{ .compatible = "nxp,lpc1850-uart" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, lpc18xx_serial_match);
+
+static struct platform_driver lpc18xx_serial_driver = {
+	.probe  = lpc18xx_serial_probe,
+	.remove = lpc18xx_serial_remove,
+	.driver = {
+		.name = "lpc18xx-uart",
+		.of_match_table = lpc18xx_serial_match,
+	},
+};
+module_platform_driver(lpc18xx_serial_driver);
+
+MODULE_AUTHOR("Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
+MODULE_DESCRIPTION("Serial port driver NXP LPC18xx/43xx devices");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index c35070356528..46f25fb8fbab 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -336,6 +336,14 @@ config SERIAL_8250_FINTEK
 	  LPC to 4 UART. This device has some RS485 functionality not available
 	  through the PNP driver. If unsure, say N.
 
+config SERIAL_8250_LPC18XX
+	bool "NXP LPC18xx/43xx serial port support"
+	depends on SERIAL_8250 && OF && (ARCH_LPC18XX || COMPILE_TEST)
+	default ARCH_LPC18XX
+	help
+	  If you have a LPC18xx/43xx based board and want to use the
+	  serial port, say Y to this option. If unsure, say Y.
+
 config SERIAL_8250_MT6577
 	bool "Mediatek serial port support"
 	depends on SERIAL_8250 && ARCH_MEDIATEK
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 31e7cdc6865c..74d7c311cf4f 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -22,4 +22,5 @@ obj-$(CONFIG_SERIAL_8250_DW)		+= 8250_dw.o
 obj-$(CONFIG_SERIAL_8250_EM)		+= 8250_em.o
 obj-$(CONFIG_SERIAL_8250_OMAP)		+= 8250_omap.o
 obj-$(CONFIG_SERIAL_8250_FINTEK)	+= 8250_fintek.o
+obj-$(CONFIG_SERIAL_8250_LPC18XX)	+= 8250_lpc18xx.o
 obj-$(CONFIG_SERIAL_8250_MT6577)	+= 8250_mtk.o
-- 
1.8.0

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[PATCH v2 2/2] doc: dt: add documentation for nxp,lpc1850-uart

[Joachim Eastwood]

Add device tree binding documentation for nxp,lpc1850-uart.

Signed-off-by: Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 .../bindings/serial/nxp,lpc1850-uart.txt           | 28 ++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/nxp,lpc1850-uart.txt

diff --git a/Documentation/devicetree/bindings/serial/nxp,lpc1850-uart.txt b/Documentation/devicetree/bindings/serial/nxp,lpc1850-uart.txt
new file mode 100644
index 000000000000..04e23e63ee4f
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/nxp,lpc1850-uart.txt
@@ -0,0 +1,28 @@
+* NXP LPC1850 UART
+
+Required properties:
+- compatible	: "nxp,lpc1850-uart", "ns16550a".
+- reg		: offset and length of the register set for the device.
+- interrupts	: should contain uart interrupt.
+- clocks	: phandle to the input clocks.
+- clock-names	: required elements: "uartclk", "reg".
+
+Optional properties:
+- dmas		: Two or more DMA channel specifiers following the
+		  convention outlined in bindings/dma/dma.txt
+- dma-names	: Names for the dma channels, if present. There must
+		  be at least one channel named "tx" for transmit
+		  and named "rx" for receive.
+
+Since it's also possible to also use the of_serial.c driver all
+parameters from 8250.txt also apply but are optional.
+
+Example:
+uart0: serial@40081000 {
+	compatible = "nxp,lpc1850-uart", "ns16550a";
+	reg = <0x40081000 0x1000>;
+	reg-shift = <2>;
+	interrupts = <24>;
+	clocks = <&ccu2 CLK_APB0_UART0>, <&ccu1 CLK_CPU_UART0>;
+	clock-names = "uartclk", "reg";
+};
-- 
1.8.0

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