serial: 8250_uniphier: add UniPhier serial driver

Add the driver for on-chip UART used on UniPhier SoCs.

This hardware is similar to 8250, but the register mapping is
slightly different:
  - The offset to FCR, MCR is different.
  - The divisor latch access bit does not exist.  Instead, the
    divisor latch register is available at offset 9.

This driver overrides serial_{in,out}, dl_{read,write} callbacks,
but wants to borrow most of code from 8250_core.c.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Masahiro Yamada 2015-05-29 15:04:31 +09:00 committed by Greg Kroah-Hartman
parent 0788c39b95
commit 1a8d2903cb
3 changed files with 265 additions and 0 deletions

View file

@ -0,0 +1,257 @@
/*
* 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/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
#define UNIPHIER_UART_CHAR_FCR 3 /* Character / FIFO Control Register */
#define UNIPHIER_UART_LCR_MCR 4 /* Line/Modem Control Register */
#define UNIPHIER_UART_LCR_SHIFT 8
#define UNIPHIER_UART_DLR 9 /* Divisor Latch Register */
struct uniphier8250_priv {
int line;
struct clk *clk;
spinlock_t atomic_write_lock;
};
/*
* 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 = UNIPHIER_UART_LCR_SHIFT;
/* fall through */
case UART_MCR:
offset = UNIPHIER_UART_LCR_MCR;
break;
default:
break;
}
offset <<= p->regshift;
/*
* 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 = false;
switch (offset) {
case UART_FCR:
offset = UNIPHIER_UART_CHAR_FCR;
break;
case UART_LCR:
valshift = UNIPHIER_UART_LCR_SHIFT;
/* Divisor latch access bit does not exist. */
value &= ~(UART_LCR_DLAB << valshift);
/* fall through */
case UART_MCR:
offset = UNIPHIER_UART_LCR_MCR;
break;
default:
normal = true;
break;
}
offset <<= p->regshift;
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");
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");
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 = 2;
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");
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");

View file

@ -342,3 +342,10 @@ config SERIAL_8250_MT6577
help
If you have a Mediatek based board and want to use the
serial port, say Y to this option. If unsure, say N.
config SERIAL_8250_UNIPHIER
tristate "Support for UniPhier on-chip UART"
depends on SERIAL_8250 && ARCH_UNIPHIER
help
If you have a UniPhier based board and want to use the on-chip
serial ports, say Y to this option. If unsure, say N.

View file

@ -23,3 +23,4 @@ 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_MT6577) += 8250_mtk.o
obj-$(CONFIG_SERIAL_8250_UNIPHIER) += 8250_uniphier.o