[PATCH v2 1/2] serial: 8250: add LPC18xx/43xx UART driver
Joachim Eastwood
manabian at gmail.com
Sat May 30 14:14:44 PDT 2015
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 at gmail.com>
---
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 at gmail.com>
+ *
+ * Based on 8250_mtk.c:
+ * Copyright (c) 2014 MundoReader S.L.
+ * Matthias Brugger <matthias.bgg at gmail.com>
+ *
+ * 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 at gmail.com>");
+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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