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/mod_devicetable.h>
  12#include <linux/serial_8250.h>
  13#include <linux/serial_reg.h>
  14#include <linux/platform_device.h>
  15#include <linux/clk.h>
  16#include <linux/slab.h>
  17
  18#include "8250.h"
  19
  20#define UART_DLL_EM 9
  21#define UART_DLM_EM 10
  22
  23struct serial8250_em_priv {
  24        struct clk *sclk;
  25        int line;
  26};
  27
  28static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
  29{
  30        switch (offset) {
  31        case UART_TX: /* TX @ 0x00 */
  32                writeb(value, p->membase);
  33                break;
  34        case UART_FCR: /* FCR @ 0x0c (+1) */
  35        case UART_LCR: /* LCR @ 0x10 (+1) */
  36        case UART_MCR: /* MCR @ 0x14 (+1) */
  37        case UART_SCR: /* SCR @ 0x20 (+1) */
  38                writel(value, p->membase + ((offset + 1) << 2));
  39                break;
  40        case UART_IER: /* IER @ 0x04 */
  41                value &= 0x0f; /* only 4 valid bits - not Xscale */
  42                fallthrough;
  43        case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  44        case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  45                writel(value, p->membase + (offset << 2));
  46        }
  47}
  48
  49static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
  50{
  51        switch (offset) {
  52        case UART_RX: /* RX @ 0x00 */
  53                return readb(p->membase);
  54        case UART_MCR: /* MCR @ 0x14 (+1) */
  55        case UART_LSR: /* LSR @ 0x18 (+1) */
  56        case UART_MSR: /* MSR @ 0x1c (+1) */
  57        case UART_SCR: /* SCR @ 0x20 (+1) */
  58                return readl(p->membase + ((offset + 1) << 2));
  59        case UART_IER: /* IER @ 0x04 */
  60        case UART_IIR: /* IIR @ 0x08 */
  61        case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  62        case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  63                return readl(p->membase + (offset << 2));
  64        }
  65        return 0;
  66}
  67
  68static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
  69{
  70        return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
  71}
  72
  73static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
  74{
  75        serial_out(up, UART_DLL_EM, value & 0xff);
  76        serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
  77}
  78
  79static int serial8250_em_probe(struct platform_device *pdev)
  80{
  81        struct serial8250_em_priv *priv;
  82        struct uart_8250_port up;
  83        struct resource *regs;
  84        int irq, ret;
  85
  86        irq = platform_get_irq(pdev, 0);
  87        if (irq < 0)
  88                return irq;
  89
  90        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  91        if (!regs) {
  92                dev_err(&pdev->dev, "missing registers\n");
  93                return -EINVAL;
  94        }
  95
  96        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  97        if (!priv)
  98                return -ENOMEM;
  99
 100        priv->sclk = devm_clk_get(&pdev->dev, "sclk");
 101        if (IS_ERR(priv->sclk)) {
 102                dev_err(&pdev->dev, "unable to get clock\n");
 103                return PTR_ERR(priv->sclk);
 104        }
 105
 106        memset(&up, 0, sizeof(up));
 107        up.port.mapbase = regs->start;
 108        up.port.irq = irq;
 109        up.port.type = PORT_UNKNOWN;
 110        up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
 111        up.port.dev = &pdev->dev;
 112        up.port.private_data = priv;
 113
 114        clk_prepare_enable(priv->sclk);
 115        up.port.uartclk = clk_get_rate(priv->sclk);
 116
 117        up.port.iotype = UPIO_MEM32;
 118        up.port.serial_in = serial8250_em_serial_in;
 119        up.port.serial_out = serial8250_em_serial_out;
 120        up.dl_read = serial8250_em_serial_dl_read;
 121        up.dl_write = serial8250_em_serial_dl_write;
 122
 123        ret = serial8250_register_8250_port(&up);
 124        if (ret < 0) {
 125                dev_err(&pdev->dev, "unable to register 8250 port\n");
 126                clk_disable_unprepare(priv->sclk);
 127                return ret;
 128        }
 129
 130        priv->line = ret;
 131        platform_set_drvdata(pdev, priv);
 132        return 0;
 133}
 134
 135static int serial8250_em_remove(struct platform_device *pdev)
 136{
 137        struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
 138
 139        serial8250_unregister_port(priv->line);
 140        clk_disable_unprepare(priv->sclk);
 141        return 0;
 142}
 143
 144static const struct of_device_id serial8250_em_dt_ids[] = {
 145        { .compatible = "renesas,em-uart", },
 146        {},
 147};
 148MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
 149
 150static struct platform_driver serial8250_em_platform_driver = {
 151        .driver = {
 152                .name           = "serial8250-em",
 153                .of_match_table = serial8250_em_dt_ids,
 154        },
 155        .probe                  = serial8250_em_probe,
 156        .remove                 = serial8250_em_remove,
 157};
 158
 159module_platform_driver(serial8250_em_platform_driver);
 160
 161MODULE_AUTHOR("Magnus Damm");
 162MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
 163MODULE_LICENSE("GPL v2");
 164