diff options
author | Masahiro Yamada <yamada.masahiro@socionext.com> | 2015-05-29 06:04:31 (GMT) |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-05-31 21:55:13 (GMT) |
commit | 1a8d2903cb6a92ce47cfc8841951b8227c09e505 (patch) | |
tree | ecc32f71bdbe14227ecc00272041c31566af4f03 /drivers/tty/serial/8250 | |
parent | 0788c39b955151d92711800ce14f41154095bfa6 (diff) | |
download | linux-1a8d2903cb6a92ce47cfc8841951b8227c09e505.tar.xz |
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>
Diffstat (limited to 'drivers/tty/serial/8250')
-rw-r--r-- | drivers/tty/serial/8250/8250_uniphier.c | 257 | ||||
-rw-r--r-- | drivers/tty/serial/8250/Kconfig | 7 | ||||
-rw-r--r-- | drivers/tty/serial/8250/Makefile | 1 |
3 files changed, 265 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c new file mode 100644 index 0000000..7d79425 --- /dev/null +++ b/drivers/tty/serial/8250/8250_uniphier.c @@ -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"); diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig index c350703..3e1ae446 100644 --- a/drivers/tty/serial/8250/Kconfig +++ b/drivers/tty/serial/8250/Kconfig @@ -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. diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile index 31e7cdc..f7ca8c3 100644 --- a/drivers/tty/serial/8250/Makefile +++ b/drivers/tty/serial/8250/Makefile @@ -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 |