blob: 670d2ca0f7572948384c67a49855cd96464447c1 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
*/
#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"
/*
* 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
* - No SCR (Instead, CHAR can be used as a scratch register)
* - Divisor latch at 9, no divisor latch access bit
*/
#define UNIPHIER_UART_REGSHIFT 2
/* bit[15:8] = CHAR, 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, MCR and SCR.
*/
static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
{
unsigned int valshift = 0;
switch (offset) {
case UART_SCR:
/* No SCR for this hardware. Use CHAR as a scratch register */
valshift = 8;
offset = UNIPHIER_UART_CHAR_FCR;
break;
case UART_LCR:
valshift = 8;
fallthrough;
case UART_MCR:
offset = UNIPHIER_UART_LCR_MCR;
break;
default:
offset <<= UNIPHIER_UART_REGSHIFT;
break;
}
/*
* The return value must be masked with 0xff because some registers
* share the same offset 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 = false;
switch (offset) {
case UART_SCR:
/* No SCR for this hardware. Use CHAR as a scratch register */
valshift = 8;
fallthrough;
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;
fallthrough;
case UART_MCR:
offset = UNIPHIER_UART_LCR_MCR;
break;
default:
offset <<= UNIPHIER_UART_REGSHIFT;
normal = true;
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 u32 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, u32 value)
{
writel(value, up->port.membase + UNIPHIER_UART_DLR);
}
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 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;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
memset(&up, 0, sizeof(up));
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)
return ret;
up.port.uartclk = clk_get_rate(priv->clk);
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;
ret = uart_read_port_properties(&up.port);
if (ret)
return ret;
up.port.type = PORT_16550A;
up.port.iotype = UPIO_MEM32;
up.port.fifosize = 64;
up.port.regshift = UNIPHIER_UART_REGSHIFT;
up.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE;
up.capabilities = UART_CAP_FIFO;
if (of_property_read_bool(dev->of_node, "auto-flow-control"))
up.capabilities |= UART_CAP_AFE;
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;
}
priv->line = ret;
platform_set_drvdata(pdev, priv);
return 0;
}
static void 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);
}
static int __maybe_unused uniphier_uart_suspend(struct device *dev)
{
struct uniphier8250_priv *priv = dev_get_drvdata(dev);
struct uart_8250_port *up = serial8250_get_port(priv->line);
serial8250_suspend_port(priv->line);
if (!uart_console(&up->port) || console_suspend_enabled)
clk_disable_unprepare(priv->clk);
return 0;
}
static int __maybe_unused uniphier_uart_resume(struct device *dev)
{
struct uniphier8250_priv *priv = dev_get_drvdata(dev);
struct uart_8250_port *up = serial8250_get_port(priv->line);
int ret;
if (!uart_console(&up->port) || console_suspend_enabled) {
ret = clk_prepare_enable(priv->clk);
if (ret)
return ret;
}
serial8250_resume_port(priv->line);
return 0;
}
static const struct dev_pm_ops uniphier_uart_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(uniphier_uart_suspend, uniphier_uart_resume)
};
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_new = uniphier_uart_remove,
.driver = {
.name = "uniphier-uart",
.of_match_table = uniphier_uart_match,
.pm = &uniphier_uart_pm_ops,
},
};
module_platform_driver(uniphier_uart_platform_driver);
MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
MODULE_DESCRIPTION("UniPhier UART driver");
MODULE_LICENSE("GPL");