drivers/tty/serial/8250/8250_uniphier.c - linux - Git at Google

 /*
  * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  */

 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>

 #include "8250.h"

 /* Most (but not all) of UniPhier UART devices have 64-depth FIFO. */
 #define UNIPHIER_UART_DEFAULT_FIFO_SIZE	64

 /*
  * This hardware is similar to 8250, but its register map is a bit different:
  *   - MMIO32 (regshift = 2)
  *   - FCR is not at 2, but 3
  *   - LCR and MCR are not at 3 and 4, they share 4
  *   - Divisor latch at 9, no divisor latch access bit
  */

 #define UNIPHIER_UART_REGSHIFT		2

 /* bit[15:8] = CHAR (not used), bit[7:0] = FCR */
 #define UNIPHIER_UART_CHAR_FCR		(3 << (UNIPHIER_UART_REGSHIFT))
 /* bit[15:8] = LCR, bit[7:0] = MCR */
 #define UNIPHIER_UART_LCR_MCR		(4 << (UNIPHIER_UART_REGSHIFT))
 /* Divisor Latch Register */
 #define UNIPHIER_UART_DLR		(9 << (UNIPHIER_UART_REGSHIFT))

 struct uniphier8250_priv {
 	int line;
 	struct clk *clk;
 	spinlock_t atomic_write_lock;
 };

 #ifdef CONFIG_SERIAL_8250_CONSOLE
 static int __init uniphier_early_console_setup(struct earlycon_device *device,
 					       const char *options)
 {
 	if (!device->port.membase)
 		return -ENODEV;

 	/* This hardware always expects MMIO32 register interface. */
 	device->port.iotype = UPIO_MEM32;
 	device->port.regshift = UNIPHIER_UART_REGSHIFT;

 	/*
 	 * Do not touch the divisor register in early_serial8250_setup();
 	 * we assume it has been initialized by a boot loader.
 	 */
 	device->baud = 0;

 	return early_serial8250_setup(device, options);
 }
 OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
 		    uniphier_early_console_setup);
 #endif

 /*
  * The register map is slightly different from that of 8250.
  * IO callbacks must be overridden for correct access to FCR, LCR, and MCR.
  */
 static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
 {
 	unsigned int valshift = 0;

 	switch (offset) {
 	case UART_LCR:
 		valshift = 8;
 		/* fall through */
 	case UART_MCR:
 		offset = UNIPHIER_UART_LCR_MCR;
 		break;
 	default:
 		offset <<= UNIPHIER_UART_REGSHIFT;
 		break;
 	}

 	/*
 	 * The return value must be masked with 0xff because LCR and MCR reside
 	 * in the same register that must be accessed by 32-bit write/read.
 	 * 8 or 16 bit access to this hardware result in unexpected behavior.
 	 */
 	return (readl(p->membase + offset) >> valshift) & 0xff;
 }

 static void uniphier_serial_out(struct uart_port *p, int offset, int value)
 {
 	unsigned int valshift = 0;
 	bool normal = true;

 	switch (offset) {
 	case UART_FCR:
 		offset = UNIPHIER_UART_CHAR_FCR;
 		break;
 	case UART_LCR:
 		valshift = 8;
 		/* Divisor latch access bit does not exist. */
 		value &= ~UART_LCR_DLAB;
 		/* fall through */
 	case UART_MCR:
 		offset = UNIPHIER_UART_LCR_MCR;
 		normal = false;
 		break;
 	default:
 		offset <<= UNIPHIER_UART_REGSHIFT;
 		break;
 	}

 	if (normal) {
 		writel(value, p->membase + offset);
 	} else {
 		/*
 		 * Special case: two registers share the same address that
 		 * must be 32-bit accessed.  As this is not longer atomic safe,
 		 * take a lock just in case.
 		 */
 		struct uniphier8250_priv *priv = p->private_data;
 		unsigned long flags;
 		u32 tmp;

 		spin_lock_irqsave(&priv->atomic_write_lock, flags);
 		tmp = readl(p->membase + offset);
 		tmp &= ~(0xff << valshift);
 		tmp |= value << valshift;
 		writel(tmp, p->membase + offset);
 		spin_unlock_irqrestore(&priv->atomic_write_lock, flags);
 	}
 }

 /*
  * This hardware does not have the divisor latch access bit.
  * The divisor latch register exists at different address.
  * Override dl_read/write callbacks.
  */
 static int uniphier_serial_dl_read(struct uart_8250_port *up)
 {
 	return readl(up->port.membase + UNIPHIER_UART_DLR);
 }

 static void uniphier_serial_dl_write(struct uart_8250_port *up, int value)
 {
 	writel(value, up->port.membase + UNIPHIER_UART_DLR);
 }

 static int uniphier_of_serial_setup(struct device *dev, struct uart_port *port,
 				    struct uniphier8250_priv *priv)
 {
 	int ret;
 	u32 prop;
 	struct device_node *np = dev->of_node;

 	ret = of_alias_get_id(np, "serial");
 	if (ret < 0) {
 		dev_err(dev, "failed to get alias id\n");
 		return ret;
 	}
 	port->line = priv->line = ret;

 	/* Get clk rate through clk driver */
 	priv->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(priv->clk)) {
 		dev_err(dev, "failed to get clock\n");
 		return PTR_ERR(priv->clk);
 	}

 	ret = clk_prepare_enable(priv->clk);
 	if (ret < 0)
 		return ret;

 	port->uartclk = clk_get_rate(priv->clk);

 	/* Check for fifo size */
 	if (of_property_read_u32(np, "fifo-size", &prop) == 0)
 		port->fifosize = prop;
 	else
 		port->fifosize = UNIPHIER_UART_DEFAULT_FIFO_SIZE;

 	return 0;
 }

 static int uniphier_uart_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct uart_8250_port up;
 	struct uniphier8250_priv *priv;
 	struct resource *regs;
 	void __iomem *membase;
 	int irq;
 	int ret;

 	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!regs) {
 		dev_err(dev, "failed to get memory resource\n");
 		return -EINVAL;
 	}

 	membase = devm_ioremap(dev, regs->start, resource_size(regs));
 	if (!membase)
 		return -ENOMEM;

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		dev_err(dev, "failed to get IRQ number\n");
 		return irq;
 	}

 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	memset(&up, 0, sizeof(up));

 	ret = uniphier_of_serial_setup(dev, &up.port, priv);
 	if (ret < 0)
 		return ret;

 	spin_lock_init(&priv->atomic_write_lock);

 	up.port.dev = dev;
 	up.port.private_data = priv;
 	up.port.mapbase = regs->start;
 	up.port.mapsize = resource_size(regs);
 	up.port.membase = membase;
 	up.port.irq = irq;

 	up.port.type = PORT_16550A;
 	up.port.iotype = UPIO_MEM32;
 	up.port.regshift = UNIPHIER_UART_REGSHIFT;
 	up.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE;
 	up.capabilities = UART_CAP_FIFO;

 	up.port.serial_in = uniphier_serial_in;
 	up.port.serial_out = uniphier_serial_out;
 	up.dl_read = uniphier_serial_dl_read;
 	up.dl_write = uniphier_serial_dl_write;

 	ret = serial8250_register_8250_port(&up);
 	if (ret < 0) {
 		dev_err(dev, "failed to register 8250 port\n");
 		clk_disable_unprepare(priv->clk);
 		return ret;
 	}

 	platform_set_drvdata(pdev, priv);

 	return 0;
 }

 static int uniphier_uart_remove(struct platform_device *pdev)
 {
 	struct uniphier8250_priv *priv = platform_get_drvdata(pdev);

 	serial8250_unregister_port(priv->line);
 	clk_disable_unprepare(priv->clk);

 	return 0;
 }

 static const struct of_device_id uniphier_uart_match[] = {
 	{ .compatible = "socionext,uniphier-uart" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, uniphier_uart_match);

 static struct platform_driver uniphier_uart_platform_driver = {
 	.probe		= uniphier_uart_probe,
 	.remove		= uniphier_uart_remove,
 	.driver = {
 		.name	= "uniphier-uart",
 		.of_match_table = uniphier_uart_match,
 	},
 };
 module_platform_driver(uniphier_uart_platform_driver);

 MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
 MODULE_DESCRIPTION("UniPhier UART driver");
 MODULE_LICENSE("GPL");
	/*
	* Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*/

	#include <linux/clk.h>
	#include <linux/console.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>

	#include "8250.h"

	/* Most (but not all) of UniPhier UART devices have 64-depth FIFO. */
	#define UNIPHIER_UART_DEFAULT_FIFO_SIZE 64

	/*
	* This hardware is similar to 8250, but its register map is a bit different:
	* - MMIO32 (regshift = 2)
	* - FCR is not at 2, but 3
	* - LCR and MCR are not at 3 and 4, they share 4
	* - Divisor latch at 9, no divisor latch access bit
	*/

	#define UNIPHIER_UART_REGSHIFT 2

	/* bit[15:8] = CHAR (not used), bit[7:0] = FCR */
	#define UNIPHIER_UART_CHAR_FCR (3 << (UNIPHIER_UART_REGSHIFT))
	/* bit[15:8] = LCR, bit[7:0] = MCR */
	#define UNIPHIER_UART_LCR_MCR (4 << (UNIPHIER_UART_REGSHIFT))
	/* Divisor Latch Register */
	#define UNIPHIER_UART_DLR (9 << (UNIPHIER_UART_REGSHIFT))

	struct uniphier8250_priv {
	int line;
	struct clk *clk;
	spinlock_t atomic_write_lock;
	};

	#ifdef CONFIG_SERIAL_8250_CONSOLE
	static int __init uniphier_early_console_setup(struct earlycon_device *device,
	const char *options)
	{
	if (!device->port.membase)
	return -ENODEV;

	/* This hardware always expects MMIO32 register interface. */
	device->port.iotype = UPIO_MEM32;
	device->port.regshift = UNIPHIER_UART_REGSHIFT;

	/*
	* Do not touch the divisor register in early_serial8250_setup();
	* we assume it has been initialized by a boot loader.
	*/
	device->baud = 0;

	return early_serial8250_setup(device, options);
	}
	OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
	uniphier_early_console_setup);
	#endif

	/*
	* The register map is slightly different from that of 8250.
	* IO callbacks must be overridden for correct access to FCR, LCR, and MCR.
	*/
	static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
	{
	unsigned int valshift = 0;

	switch (offset) {
	case UART_LCR:
	valshift = 8;
	/* fall through */
	case UART_MCR:
	offset = UNIPHIER_UART_LCR_MCR;
	break;
	default:
	offset <<= UNIPHIER_UART_REGSHIFT;
	break;
	}

	/*
	* The return value must be masked with 0xff because LCR and MCR reside
	* in the same register that must be accessed by 32-bit write/read.
	* 8 or 16 bit access to this hardware result in unexpected behavior.
	*/
	return (readl(p->membase + offset) >> valshift) & 0xff;
	}

	static void uniphier_serial_out(struct uart_port *p, int offset, int value)
	{
	unsigned int valshift = 0;
	bool normal = true;

	switch (offset) {
	case UART_FCR:
	offset = UNIPHIER_UART_CHAR_FCR;
	break;
	case UART_LCR:
	valshift = 8;
	/* Divisor latch access bit does not exist. */
	value &= ~UART_LCR_DLAB;
	/* fall through */
	case UART_MCR:
	offset = UNIPHIER_UART_LCR_MCR;
	normal = false;
	break;
	default:
	offset <<= UNIPHIER_UART_REGSHIFT;
	break;
	}

	if (normal) {
	writel(value, p->membase + offset);
	} else {
	/*
	* Special case: two registers share the same address that
	* must be 32-bit accessed. As this is not longer atomic safe,
	* take a lock just in case.
	*/
	struct uniphier8250_priv *priv = p->private_data;
	unsigned long flags;
	u32 tmp;

	spin_lock_irqsave(&priv->atomic_write_lock, flags);
	tmp = readl(p->membase + offset);
	tmp &= ~(0xff << valshift);
	tmp \|= value << valshift;
	writel(tmp, p->membase + offset);
	spin_unlock_irqrestore(&priv->atomic_write_lock, flags);
	}
	}

	/*
	* This hardware does not have the divisor latch access bit.
	* The divisor latch register exists at different address.
	* Override dl_read/write callbacks.
	*/
	static int uniphier_serial_dl_read(struct uart_8250_port *up)
	{
	return readl(up->port.membase + UNIPHIER_UART_DLR);
	}

	static void uniphier_serial_dl_write(struct uart_8250_port *up, int value)
	{
	writel(value, up->port.membase + UNIPHIER_UART_DLR);
	}

	static int uniphier_of_serial_setup(struct device dev, struct uart_port port,
	struct uniphier8250_priv *priv)
	{
	int ret;
	u32 prop;
	struct device_node *np = dev->of_node;

	ret = of_alias_get_id(np, "serial");
	if (ret < 0) {
	dev_err(dev, "failed to get alias id\n");
	return ret;
	}
	port->line = priv->line = ret;

	/* Get clk rate through clk driver */
	priv->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(priv->clk)) {
	dev_err(dev, "failed to get clock\n");
	return PTR_ERR(priv->clk);
	}

	ret = clk_prepare_enable(priv->clk);
	if (ret < 0)
	return ret;

	port->uartclk = clk_get_rate(priv->clk);

	/* Check for fifo size */
	if (of_property_read_u32(np, "fifo-size", &prop) == 0)
	port->fifosize = prop;
	else
	port->fifosize = UNIPHIER_UART_DEFAULT_FIFO_SIZE;

	return 0;
	}

	static int uniphier_uart_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct uart_8250_port up;
	struct uniphier8250_priv *priv;
	struct resource *regs;
	void __iomem *membase;
	int irq;
	int ret;

	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!regs) {
	dev_err(dev, "failed to get memory resource\n");
	return -EINVAL;
	}

	membase = devm_ioremap(dev, regs->start, resource_size(regs));
	if (!membase)
	return -ENOMEM;

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	dev_err(dev, "failed to get IRQ number\n");
	return irq;
	}

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
	return -ENOMEM;

	memset(&up, 0, sizeof(up));

	ret = uniphier_of_serial_setup(dev, &up.port, priv);
	if (ret < 0)
	return ret;

	spin_lock_init(&priv->atomic_write_lock);

	up.port.dev = dev;
	up.port.private_data = priv;
	up.port.mapbase = regs->start;
	up.port.mapsize = resource_size(regs);
	up.port.membase = membase;
	up.port.irq = irq;

	up.port.type = PORT_16550A;
	up.port.iotype = UPIO_MEM32;
	up.port.regshift = UNIPHIER_UART_REGSHIFT;
	up.port.flags = UPF_FIXED_PORT \| UPF_FIXED_TYPE;
	up.capabilities = UART_CAP_FIFO;

	up.port.serial_in = uniphier_serial_in;
	up.port.serial_out = uniphier_serial_out;
	up.dl_read = uniphier_serial_dl_read;
	up.dl_write = uniphier_serial_dl_write;

	ret = serial8250_register_8250_port(&up);
	if (ret < 0) {
	dev_err(dev, "failed to register 8250 port\n");
	clk_disable_unprepare(priv->clk);
	return ret;
	}

	platform_set_drvdata(pdev, priv);

	return 0;
	}

	static int uniphier_uart_remove(struct platform_device *pdev)
	{
	struct uniphier8250_priv *priv = platform_get_drvdata(pdev);

	serial8250_unregister_port(priv->line);
	clk_disable_unprepare(priv->clk);

	return 0;
	}

	static const struct of_device_id uniphier_uart_match[] = {
	{ .compatible = "socionext,uniphier-uart" },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, uniphier_uart_match);

	static struct platform_driver uniphier_uart_platform_driver = {
	.probe = uniphier_uart_probe,
	.remove = uniphier_uart_remove,
	.driver = {
	.name = "uniphier-uart",
	.of_match_table = uniphier_uart_match,
	},
	};
	module_platform_driver(uniphier_uart_platform_driver);

	MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
	MODULE_DESCRIPTION("UniPhier UART driver");
	MODULE_LICENSE("GPL");