LXR linux/drivers/tty/serial/8250/8250

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Renesas Emma Mobile 8250 driver
   4 *
   5 *  Copyright (C) 2012 Magnus Damm
   6 */
   7
   8#include <linux/device.h>
   9#include <linux/io.h>
  10#include <linux/module.h>
  11#include <linux/serial_8250.h>
  12#include <linux/serial_reg.h>
  13#include <linux/platform_device.h>
  14#include <linux/clk.h>
  15#include <linux/slab.h>
  16
  17#include "8250.h"
  18
  19#define UART_DLL_EM 9
  20#define UART_DLM_EM 10
  21
  22struct serial8250_em_priv {
  23        struct clk *sclk;
  24        int line;
  25};
  26
  27static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
  28{
  29        switch (offset) {
  30        case UART_TX: /* TX @ 0x00 */
  31                writeb(value, p->membase);
  32                break;
  33        case UART_FCR: /* FCR @ 0x0c (+1) */
  34        case UART_LCR: /* LCR @ 0x10 (+1) */
  35        case UART_MCR: /* MCR @ 0x14 (+1) */
  36        case UART_SCR: /* SCR @ 0x20 (+1) */
  37                writel(value, p->membase + ((offset + 1) << 2));
  38                break;
  39        case UART_IER: /* IER @ 0x04 */
  40                value &= 0x0f; /* only 4 valid bits - not Xscale */
  41                /* fall-through */
  42        case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  43        case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  44                writel(value, p->membase + (offset << 2));
  45        }
  46}
  47
  48static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
  49{
  50        switch (offset) {
  51        case UART_RX: /* RX @ 0x00 */
  52                return readb(p->membase);
  53        case UART_MCR: /* MCR @ 0x14 (+1) */
  54        case UART_LSR: /* LSR @ 0x18 (+1) */
  55        case UART_MSR: /* MSR @ 0x1c (+1) */
  56        case UART_SCR: /* SCR @ 0x20 (+1) */
  57                return readl(p->membase + ((offset + 1) << 2));
  58        case UART_IER: /* IER @ 0x04 */
  59        case UART_IIR: /* IIR @ 0x08 */
  60        case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  61        case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  62                return readl(p->membase + (offset << 2));
  63        }
  64        return 0;
  65}
  66
  67static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
  68{
  69        return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
  70}
  71
  72static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
  73{
  74        serial_out(up, UART_DLL_EM, value & 0xff);
  75        serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
  76}
  77
  78static int serial8250_em_probe(struct platform_device *pdev)
  79{
  80        struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  81        struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  82        struct serial8250_em_priv *priv;
  83        struct uart_8250_port up;
  84        int ret;
  85
  86        if (!regs || !irq) {
  87                dev_err(&pdev->dev, "missing registers or irq\n");
  88                return -EINVAL;
  89        }
  90
  91        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  92        if (!priv)
  93                return -ENOMEM;
  94
  95        priv->sclk = devm_clk_get(&pdev->dev, "sclk");
  96        if (IS_ERR(priv->sclk)) {
  97                dev_err(&pdev->dev, "unable to get clock\n");
  98                return PTR_ERR(priv->sclk);
  99        }
 100
 101        memset(&up, 0, sizeof(up));
 102        up.port.mapbase = regs->start;
 103        up.port.irq = irq->start;
 104        up.port.type = PORT_UNKNOWN;
 105        up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
 106        up.port.dev = &pdev->dev;
 107        up.port.private_data = priv;
 108
 109        clk_prepare_enable(priv->sclk);
 110        up.port.uartclk = clk_get_rate(priv->sclk);
 111
 112        up.port.iotype = UPIO_MEM32;
 113        up.port.serial_in = serial8250_em_serial_in;
 114        up.port.serial_out = serial8250_em_serial_out;
 115        up.dl_read = serial8250_em_serial_dl_read;
 116        up.dl_write = serial8250_em_serial_dl_write;
 117
 118        ret = serial8250_register_8250_port(&up);
 119        if (ret < 0) {
 120                dev_err(&pdev->dev, "unable to register 8250 port\n");
 121                clk_disable_unprepare(priv->sclk);
 122                return ret;
 123        }
 124
 125        priv->line = ret;
 126        platform_set_drvdata(pdev, priv);
 127        return 0;
 128}
 129
 130static int serial8250_em_remove(struct platform_device *pdev)
 131{
 132        struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
 133
 134        serial8250_unregister_port(priv->line);
 135        clk_disable_unprepare(priv->sclk);
 136        return 0;
 137}
 138
 139static const struct of_device_id serial8250_em_dt_ids[] = {
 140        { .compatible = "renesas,em-uart", },
 141        {},
 142};
 143MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
 144
 145static struct platform_driver serial8250_em_platform_driver = {
 146        .driver = {
 147                .name           = "serial8250-em",
 148                .of_match_table = serial8250_em_dt_ids,
 149        },
 150        .probe                  = serial8250_em_probe,
 151        .remove                 = serial8250_em_remove,
 152};
 153
 154module_platform_driver(serial8250_em_platform_driver);
 155
 156MODULE_AUTHOR("Magnus Damm");
 157MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
 158MODULE_LICENSE("GPL v2");
 159