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
Greg Kroah-Hartman
parent
0788c39b95
commit
1a8d2903cb
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@ -0,0 +1,257 @@
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/*
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* Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include "8250.h"
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/* Most (but not all) of UniPhier UART devices have 64-depth FIFO. */
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#define UNIPHIER_UART_DEFAULT_FIFO_SIZE 64
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#define UNIPHIER_UART_CHAR_FCR 3 /* Character / FIFO Control Register */
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#define UNIPHIER_UART_LCR_MCR 4 /* Line/Modem Control Register */
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#define UNIPHIER_UART_LCR_SHIFT 8
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#define UNIPHIER_UART_DLR 9 /* Divisor Latch Register */
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struct uniphier8250_priv {
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int line;
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struct clk *clk;
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spinlock_t atomic_write_lock;
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};
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/*
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* The register map is slightly different from that of 8250.
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* IO callbacks must be overridden for correct access to FCR, LCR, and MCR.
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*/
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static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
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{
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unsigned int valshift = 0;
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switch (offset) {
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case UART_LCR:
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valshift = UNIPHIER_UART_LCR_SHIFT;
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/* fall through */
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case UART_MCR:
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offset = UNIPHIER_UART_LCR_MCR;
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break;
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default:
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break;
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}
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offset <<= p->regshift;
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/*
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* The return value must be masked with 0xff because LCR and MCR reside
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* in the same register that must be accessed by 32-bit write/read.
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* 8 or 16 bit access to this hardware result in unexpected behavior.
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*/
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return (readl(p->membase + offset) >> valshift) & 0xff;
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}
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static void uniphier_serial_out(struct uart_port *p, int offset, int value)
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{
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unsigned int valshift = 0;
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bool normal = false;
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switch (offset) {
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case UART_FCR:
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offset = UNIPHIER_UART_CHAR_FCR;
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break;
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case UART_LCR:
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valshift = UNIPHIER_UART_LCR_SHIFT;
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/* Divisor latch access bit does not exist. */
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value &= ~(UART_LCR_DLAB << valshift);
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/* fall through */
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case UART_MCR:
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offset = UNIPHIER_UART_LCR_MCR;
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break;
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default:
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normal = true;
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break;
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}
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offset <<= p->regshift;
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if (normal) {
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writel(value, p->membase + offset);
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} else {
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/*
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* Special case: two registers share the same address that
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* must be 32-bit accessed. As this is not longer atomic safe,
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* take a lock just in case.
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*/
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struct uniphier8250_priv *priv = p->private_data;
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unsigned long flags;
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u32 tmp;
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spin_lock_irqsave(&priv->atomic_write_lock, flags);
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tmp = readl(p->membase + offset);
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tmp &= ~(0xff << valshift);
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tmp |= value << valshift;
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writel(tmp, p->membase + offset);
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spin_unlock_irqrestore(&priv->atomic_write_lock, flags);
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}
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}
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/*
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* This hardware does not have the divisor latch access bit.
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* The divisor latch register exists at different address.
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* Override dl_read/write callbacks.
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*/
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static int uniphier_serial_dl_read(struct uart_8250_port *up)
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{
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return readl(up->port.membase + UNIPHIER_UART_DLR);
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}
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static void uniphier_serial_dl_write(struct uart_8250_port *up, int value)
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{
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writel(value, up->port.membase + UNIPHIER_UART_DLR);
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}
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static int uniphier_of_serial_setup(struct device *dev, struct uart_port *port,
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struct uniphier8250_priv *priv)
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{
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int ret;
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u32 prop;
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struct device_node *np = dev->of_node;
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ret = of_alias_get_id(np, "serial");
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if (ret < 0) {
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dev_err(dev, "failed to get alias id\n");
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return ret;
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}
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port->line = priv->line = ret;
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/* Get clk rate through clk driver */
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priv->clk = devm_clk_get(dev, NULL);
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if (IS_ERR(priv->clk)) {
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dev_err(dev, "failed to get clock\n");
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return PTR_ERR(priv->clk);
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}
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ret = clk_prepare_enable(priv->clk);
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if (ret < 0)
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return ret;
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port->uartclk = clk_get_rate(priv->clk);
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/* Check for fifo size */
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if (of_property_read_u32(np, "fifo-size", &prop) == 0)
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port->fifosize = prop;
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else
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port->fifosize = UNIPHIER_UART_DEFAULT_FIFO_SIZE;
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return 0;
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}
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static int uniphier_uart_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct uart_8250_port up;
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struct uniphier8250_priv *priv;
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struct resource *regs;
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void __iomem *membase;
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int irq;
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int ret;
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regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!regs) {
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dev_err(dev, "failed to get memory resource");
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return -EINVAL;
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}
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membase = devm_ioremap(dev, regs->start, resource_size(regs));
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if (!membase)
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return -ENOMEM;
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irq = platform_get_irq(pdev, 0);
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if (irq < 0) {
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dev_err(dev, "failed to get IRQ number");
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return irq;
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}
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priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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memset(&up, 0, sizeof(up));
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ret = uniphier_of_serial_setup(dev, &up.port, priv);
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if (ret < 0)
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return ret;
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spin_lock_init(&priv->atomic_write_lock);
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up.port.dev = dev;
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up.port.private_data = priv;
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up.port.mapbase = regs->start;
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up.port.mapsize = resource_size(regs);
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up.port.membase = membase;
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up.port.irq = irq;
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up.port.type = PORT_16550A;
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up.port.iotype = UPIO_MEM32;
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up.port.regshift = 2;
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up.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE;
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up.capabilities = UART_CAP_FIFO;
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up.port.serial_in = uniphier_serial_in;
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up.port.serial_out = uniphier_serial_out;
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up.dl_read = uniphier_serial_dl_read;
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up.dl_write = uniphier_serial_dl_write;
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ret = serial8250_register_8250_port(&up);
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if (ret < 0) {
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dev_err(dev, "failed to register 8250 port\n");
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return ret;
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}
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platform_set_drvdata(pdev, priv);
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return 0;
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}
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static int uniphier_uart_remove(struct platform_device *pdev)
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{
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struct uniphier8250_priv *priv = platform_get_drvdata(pdev);
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serial8250_unregister_port(priv->line);
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clk_disable_unprepare(priv->clk);
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return 0;
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}
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static const struct of_device_id uniphier_uart_match[] = {
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{ .compatible = "socionext,uniphier-uart" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, uniphier_uart_match);
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static struct platform_driver uniphier_uart_platform_driver = {
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.probe = uniphier_uart_probe,
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.remove = uniphier_uart_remove,
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.driver = {
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.name = "uniphier-uart",
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.of_match_table = uniphier_uart_match,
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},
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};
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module_platform_driver(uniphier_uart_platform_driver);
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MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
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MODULE_DESCRIPTION("UniPhier UART driver");
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MODULE_LICENSE("GPL");
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@ -342,3 +342,10 @@ config SERIAL_8250_MT6577
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help
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If you have a Mediatek based board and want to use the
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serial port, say Y to this option. If unsure, say N.
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config SERIAL_8250_UNIPHIER
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tristate "Support for UniPhier on-chip UART"
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depends on SERIAL_8250 && ARCH_UNIPHIER
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help
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If you have a UniPhier based board and want to use the on-chip
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serial ports, say Y to this option. If unsure, say N.
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@ -23,3 +23,4 @@ obj-$(CONFIG_SERIAL_8250_EM) += 8250_em.o
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obj-$(CONFIG_SERIAL_8250_OMAP) += 8250_omap.o
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obj-$(CONFIG_SERIAL_8250_FINTEK) += 8250_fintek.o
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obj-$(CONFIG_SERIAL_8250_MT6577) += 8250_mtk.o
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obj-$(CONFIG_SERIAL_8250_UNIPHIER) += 8250_uniphier.o
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