diff options
Diffstat (limited to 'kernel/drivers/tty/serial/8250/8250_uniphier.c')
| -rw-r--r-- | kernel/drivers/tty/serial/8250/8250_uniphier.c | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/kernel/drivers/tty/serial/8250/8250_uniphier.c b/kernel/drivers/tty/serial/8250/8250_uniphier.c new file mode 100644 index 000000000..245edbb68 --- /dev/null +++ b/kernel/drivers/tty/serial/8250/8250_uniphier.c @@ -0,0 +1,262 @@ +/* + * 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) +{ + int offset = UNIPHIER_UART_DLR << up->port.regshift; + + return readl(up->port.membase + offset); +} + +static void uniphier_serial_dl_write(struct uart_8250_port *up, int value) +{ + int offset = UNIPHIER_UART_DLR << up->port.regshift; + + writel(value, up->port.membase + offset); +} + +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"); + 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"); |