/*
 * Copyright (C) 2010 Lars-Peter Clausen <lars@metafoo.de>
 * Copyright (C) 2015 Imagination Technologies
 *
 * Ingenic SoC UART support
 *
 * 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.
 *
 * You should have received a copy of the  GNU General Public License along
 * with this program; if not, write  to the Free Software Foundation, Inc.,
 * 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/clk.h>
#include <linux/console.h>
#include <linux/io.h>
#include <linux/libfdt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/platform_device.h>
#include <linux/serial_8250.h>
#include <linux/serial_core.h>
#include <linux/serial_reg.h>

struct ingenic_uart_data {
	struct clk	*clk_module;
	struct clk	*clk_baud;
	int		line;
};

#define UART_FCR_UME	BIT(4)

static struct earlycon_device *early_device;

static uint8_t __init early_in(struct uart_port *port, int offset)
{
	return readl(port->membase + (offset << 2));
}

static void __init early_out(struct uart_port *port, int offset, uint8_t value)
{
	writel(value, port->membase + (offset << 2));
}

static void __init ingenic_early_console_putc(struct uart_port *port, int c)
{
	uint8_t lsr;

	do {
		lsr = early_in(port, UART_LSR);
	} while ((lsr & UART_LSR_TEMT) == 0);

	early_out(port, UART_TX, c);
}

static void __init ingenic_early_console_write(struct console *console,
					      const char *s, unsigned int count)
{
	uart_console_write(&early_device->port, s, count,
			   ingenic_early_console_putc);
}

static void __init ingenic_early_console_setup_clock(struct earlycon_device *dev)
{
	void *fdt = initial_boot_params;
	const __be32 *prop;
	int offset;

	offset = fdt_path_offset(fdt, "/ext");
	if (offset < 0)
		return;

	prop = fdt_getprop(fdt, offset, "clock-frequency", NULL);
	if (!prop)
		return;

	dev->port.uartclk = be32_to_cpup(prop);
}

static int __init ingenic_early_console_setup(struct earlycon_device *dev,
					      const char *opt)
{
	struct uart_port *port = &dev->port;
	unsigned int baud, divisor;

	if (!dev->port.membase)
		return -ENODEV;

	ingenic_early_console_setup_clock(dev);

	baud = dev->baud ?: 115200;
	divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * baud);

	early_out(port, UART_IER, 0);
	early_out(port, UART_LCR, UART_LCR_DLAB | UART_LCR_WLEN8);
	early_out(port, UART_DLL, 0);
	early_out(port, UART_DLM, 0);
	early_out(port, UART_LCR, UART_LCR_WLEN8);
	early_out(port, UART_FCR, UART_FCR_UME | UART_FCR_CLEAR_XMIT |
			UART_FCR_CLEAR_RCVR | UART_FCR_ENABLE_FIFO);
	early_out(port, UART_MCR, UART_MCR_RTS | UART_MCR_DTR);

	early_out(port, UART_LCR, UART_LCR_DLAB | UART_LCR_WLEN8);
	early_out(port, UART_DLL, divisor & 0xff);
	early_out(port, UART_DLM, (divisor >> 8) & 0xff);
	early_out(port, UART_LCR, UART_LCR_WLEN8);

	early_device = dev;
	dev->con->write = ingenic_early_console_write;

	return 0;
}

EARLYCON_DECLARE(jz4740_uart, ingenic_early_console_setup);
OF_EARLYCON_DECLARE(jz4740_uart, "ingenic,jz4740-uart",
		    ingenic_early_console_setup);

EARLYCON_DECLARE(jz4775_uart, ingenic_early_console_setup);
OF_EARLYCON_DECLARE(jz4775_uart, "ingenic,jz4775-uart",
		    ingenic_early_console_setup);

EARLYCON_DECLARE(jz4780_uart, ingenic_early_console_setup);
OF_EARLYCON_DECLARE(jz4780_uart, "ingenic,jz4780-uart",
		    ingenic_early_console_setup);

static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value)
{
	switch (offset) {
	case UART_FCR:
		/* UART module enable */
		value |= UART_FCR_UME;
		break;

	case UART_IER:
		value |= (value & 0x4) << 2;
		break;

	default:
		break;
	}

	writeb(value, p->membase + (offset << p->regshift));
}

static int ingenic_uart_probe(struct platform_device *pdev)
{
	struct uart_8250_port uart = {};
	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	struct ingenic_uart_data *data;
	int err, line;

	if (!regs || !irq) {
		dev_err(&pdev->dev, "no registers/irq defined\n");
		return -EINVAL;
	}

	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	spin_lock_init(&uart.port.lock);
	uart.port.type = PORT_16550;
	uart.port.flags = UPF_SKIP_TEST | UPF_IOREMAP | UPF_FIXED_TYPE;
	uart.port.iotype = UPIO_MEM;
	uart.port.mapbase = regs->start;
	uart.port.regshift = 2;
	uart.port.serial_out = ingenic_uart_serial_out;
	uart.port.irq = irq->start;
	uart.port.dev = &pdev->dev;

	/* Check for a fixed line number */
	line = of_alias_get_id(pdev->dev.of_node, "serial");
	if (line >= 0)
		uart.port.line = line;

	uart.port.membase = devm_ioremap(&pdev->dev, regs->start,
					 resource_size(regs));
	if (!uart.port.membase)
		return -ENOMEM;

	data->clk_module = devm_clk_get(&pdev->dev, "module");
	if (IS_ERR(data->clk_module)) {
		err = PTR_ERR(data->clk_module);
		if (err != -EPROBE_DEFER)
			dev_err(&pdev->dev,
				"unable to get module clock: %d\n", err);
		return err;
	}

	data->clk_baud = devm_clk_get(&pdev->dev, "baud");
	if (IS_ERR(data->clk_baud)) {
		err = PTR_ERR(data->clk_baud);
		if (err != -EPROBE_DEFER)
			dev_err(&pdev->dev,
				"unable to get baud clock: %d\n", err);
		return err;
	}

	err = clk_prepare_enable(data->clk_module);
	if (err) {
		dev_err(&pdev->dev, "could not enable module clock: %d\n", err);
		goto out;
	}

	err = clk_prepare_enable(data->clk_baud);
	if (err) {
		dev_err(&pdev->dev, "could not enable baud clock: %d\n", err);
		goto out_disable_moduleclk;
	}
	uart.port.uartclk = clk_get_rate(data->clk_baud);

	data->line = serial8250_register_8250_port(&uart);
	if (data->line < 0) {
		err = data->line;
		goto out_disable_baudclk;
	}

	platform_set_drvdata(pdev, data);
	return 0;

out_disable_baudclk:
	clk_disable_unprepare(data->clk_baud);
out_disable_moduleclk:
	clk_disable_unprepare(data->clk_module);
out:
	return err;
}

static int ingenic_uart_remove(struct platform_device *pdev)
{
	struct ingenic_uart_data *data = platform_get_drvdata(pdev);

	serial8250_unregister_port(data->line);
	clk_disable_unprepare(data->clk_module);
	clk_disable_unprepare(data->clk_baud);
	return 0;
}

static const struct of_device_id of_match[] = {
	{ .compatible = "ingenic,jz4740-uart" },
	{ .compatible = "ingenic,jz4775-uart" },
	{ .compatible = "ingenic,jz4780-uart" },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, of_match);

static struct platform_driver ingenic_uart_platform_driver = {
	.driver = {
		.name		= "ingenic-uart",
		.owner		= THIS_MODULE,
		.of_match_table	= of_match,
	},
	.probe			= ingenic_uart_probe,
	.remove			= ingenic_uart_remove,
};

module_platform_driver(ingenic_uart_platform_driver);

MODULE_AUTHOR("Paul Burton");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Ingenic SoC UART driver");