drivers/tty/serial/8250/8250_em.c

   1 /*
   2  * Renesas Emma Mobile 8250 driver
   3  *
   4  *  Copyright (C) 2012 Magnus Damm
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 #include <linux/device.h>
  21 #include <linux/io.h>
  22 #include <linux/module.h>
  23 #include <linux/serial_8250.h>
  24 #include <linux/serial_reg.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/clk.h>
  27 #include <linux/slab.h>
  28
  29 #include "8250.h"
  30
  31 #define UART_DLL_EM 9
  32 #define UART_DLM_EM 10
  33
  34 struct serial8250_em_priv {
  35         struct clk *sclk;
  36         int line;
  37 };
  38
  39 static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
  40 {
  41         switch (offset) {
  42         case UART_TX: /* TX @ 0x00 */
  43                 writeb(value, p->membase);
  44                 break;
  45         case UART_FCR: /* FCR @ 0x0c (+1) */
  46         case UART_LCR: /* LCR @ 0x10 (+1) */
  47         case UART_MCR: /* MCR @ 0x14 (+1) */
  48         case UART_SCR: /* SCR @ 0x20 (+1) */
  49                 writel(value, p->membase + ((offset + 1) << 2));
  50                 break;
  51         case UART_IER: /* IER @ 0x04 */
  52                 value &= 0x0f; /* only 4 valid bits - not Xscale */
  53                 /* fall-through */
  54         case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  55         case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  56                 writel(value, p->membase + (offset << 2));
  57         }
  58 }
  59
  60 static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
  61 {
  62         switch (offset) {
  63         case UART_RX: /* RX @ 0x00 */
  64                 return readb(p->membase);
  65         case UART_MCR: /* MCR @ 0x14 (+1) */
  66         case UART_LSR: /* LSR @ 0x18 (+1) */
  67         case UART_MSR: /* MSR @ 0x1c (+1) */
  68         case UART_SCR: /* SCR @ 0x20 (+1) */
  69                 return readl(p->membase + ((offset + 1) << 2));
  70         case UART_IER: /* IER @ 0x04 */
  71         case UART_IIR: /* IIR @ 0x08 */
  72         case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  73         case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  74                 return readl(p->membase + (offset << 2));
  75         }
  76         return 0;
  77 }
  78
  79 static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
  80 {
  81         return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
  82 }
  83
  84 static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
  85 {
  86         serial_out(up, UART_DLL_EM, value & 0xff);
  87         serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
  88 }
  89
  90 static int serial8250_em_probe(struct platform_device *pdev)
  91 {
  92         struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  93         struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  94         struct serial8250_em_priv *priv;
  95         struct uart_8250_port up;
  96         int ret;
  97
  98         if (!regs || !irq) {
  99                 dev_err(&pdev->dev, "missing registers or irq\n");
 100                 return -EINVAL;
 101         }
 102
 103         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 104         if (!priv)
 105                 return -ENOMEM;
 106
 107         priv->sclk = devm_clk_get(&pdev->dev, "sclk");
 108         if (IS_ERR(priv->sclk)) {
 109                 dev_err(&pdev->dev, "unable to get clock\n");
 110                 return PTR_ERR(priv->sclk);
 111         }
 112
 113         memset(&up, 0, sizeof(up));
 114         up.port.mapbase = regs->start;
 115         up.port.irq = irq->start;
 116         up.port.type = PORT_UNKNOWN;
 117         up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
 118         up.port.dev = &pdev->dev;
 119         up.port.private_data = priv;
 120
 121         clk_prepare_enable(priv->sclk);
 122         up.port.uartclk = clk_get_rate(priv->sclk);
 123
 124         up.port.iotype = UPIO_MEM32;
 125         up.port.serial_in = serial8250_em_serial_in;
 126         up.port.serial_out = serial8250_em_serial_out;
 127         up.dl_read = serial8250_em_serial_dl_read;
 128         up.dl_write = serial8250_em_serial_dl_write;
 129
 130         ret = serial8250_register_8250_port(&up);
 131         if (ret < 0) {
 132                 dev_err(&pdev->dev, "unable to register 8250 port\n");
 133                 clk_disable_unprepare(priv->sclk);
 134                 return ret;
 135         }
 136
 137         priv->line = ret;
 138         platform_set_drvdata(pdev, priv);
 139         return 0;
 140 }
 141
 142 static int serial8250_em_remove(struct platform_device *pdev)
 143 {
 144         struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
 145
 146         serial8250_unregister_port(priv->line);
 147         clk_disable_unprepare(priv->sclk);
 148         return 0;
 149 }
 150
 151 static const struct of_device_id serial8250_em_dt_ids[] = {
 152         { .compatible = "renesas,em-uart", },
 153         {},
 154 };
 155 MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
 156
 157 static struct platform_driver serial8250_em_platform_driver = {
 158         .driver = {
 159                 .name           = "serial8250-em",
 160                 .of_match_table = serial8250_em_dt_ids,
 161         },
 162         .probe                  = serial8250_em_probe,
 163         .remove                 = serial8250_em_remove,
 164 };
 165
 166 module_platform_driver(serial8250_em_platform_driver);
 167
 168 MODULE_AUTHOR("Magnus Damm");
 169 MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
 170 MODULE_LICENSE("GPL v2");