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/init.h>
  22 #include <linux/io.h>
  23 #include <linux/module.h>
  24 #include <linux/serial_8250.h>
  25 #include <linux/serial_core.h>
  26 #include <linux/serial_reg.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/clk.h>
  29 #include <linux/slab.h>
  30
  31 #include "8250.h"
  32
  33 #define UART_DLL_EM 9
  34 #define UART_DLM_EM 10
  35
  36 struct serial8250_em_priv {
  37         struct clk *sclk;
  38         int line;
  39 };
  40
  41 static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
  42 {
  43         switch (offset) {
  44         case UART_TX: /* TX @ 0x00 */
  45                 writeb(value, p->membase);
  46                 break;
  47         case UART_FCR: /* FCR @ 0x0c (+1) */
  48         case UART_LCR: /* LCR @ 0x10 (+1) */
  49         case UART_MCR: /* MCR @ 0x14 (+1) */
  50         case UART_SCR: /* SCR @ 0x20 (+1) */
  51                 writel(value, p->membase + ((offset + 1) << 2));
  52                 break;
  53         case UART_IER: /* IER @ 0x04 */
  54                 value &= 0x0f; /* only 4 valid bits - not Xscale */
  55                 /* fall-through */
  56         case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  57         case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  58                 writel(value, p->membase + (offset << 2));
  59         }
  60 }
  61
  62 static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
  63 {
  64         switch (offset) {
  65         case UART_RX: /* RX @ 0x00 */
  66                 return readb(p->membase);
  67         case UART_MCR: /* MCR @ 0x14 (+1) */
  68         case UART_LSR: /* LSR @ 0x18 (+1) */
  69         case UART_MSR: /* MSR @ 0x1c (+1) */
  70         case UART_SCR: /* SCR @ 0x20 (+1) */
  71                 return readl(p->membase + ((offset + 1) << 2));
  72         case UART_IER: /* IER @ 0x04 */
  73         case UART_IIR: /* IIR @ 0x08 */
  74         case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  75         case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  76                 return readl(p->membase + (offset << 2));
  77         }
  78         return 0;
  79 }
  80
  81 static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
  82 {
  83         return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
  84 }
  85
  86 static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
  87 {
  88         serial_out(up, UART_DLL_EM, value & 0xff);
  89         serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
  90 }
  91
  92 static int serial8250_em_probe(struct platform_device *pdev)
  93 {
  94         struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  95         struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  96         struct serial8250_em_priv *priv;
  97         struct uart_8250_port up;
  98         int ret;
  99
 100         if (!regs || !irq) {
 101                 dev_err(&pdev->dev, "missing registers or irq\n");
 102                 return -EINVAL;
 103         }
 104
 105         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 106         if (!priv) {
 107                 dev_err(&pdev->dev, "unable to allocate private data\n");
 108                 return -ENOMEM;
 109         }
 110
 111         priv->sclk = devm_clk_get(&pdev->dev, "sclk");
 112         if (IS_ERR(priv->sclk)) {
 113                 dev_err(&pdev->dev, "unable to get clock\n");
 114                 return PTR_ERR(priv->sclk);
 115         }
 116
 117         memset(&up, 0, sizeof(up));
 118         up.port.mapbase = regs->start;
 119         up.port.irq = irq->start;
 120         up.port.type = PORT_UNKNOWN;
 121         up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
 122         up.port.dev = &pdev->dev;
 123         up.port.private_data = priv;
 124
 125         clk_enable(priv->sclk);
 126         up.port.uartclk = clk_get_rate(priv->sclk);
 127
 128         up.port.iotype = UPIO_MEM32;
 129         up.port.serial_in = serial8250_em_serial_in;
 130         up.port.serial_out = serial8250_em_serial_out;
 131         up.dl_read = serial8250_em_serial_dl_read;
 132         up.dl_write = serial8250_em_serial_dl_write;
 133
 134         ret = serial8250_register_8250_port(&up);
 135         if (ret < 0) {
 136                 dev_err(&pdev->dev, "unable to register 8250 port\n");
 137                 clk_disable(priv->sclk);
 138                 return ret;
 139         }
 140
 141         priv->line = ret;
 142         platform_set_drvdata(pdev, priv);
 143         return 0;
 144 }
 145
 146 static int serial8250_em_remove(struct platform_device *pdev)
 147 {
 148         struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
 149
 150         serial8250_unregister_port(priv->line);
 151         clk_disable(priv->sclk);
 152         return 0;
 153 }
 154
 155 static const struct of_device_id serial8250_em_dt_ids[] = {
 156         { .compatible = "renesas,em-uart", },
 157         {},
 158 };
 159 MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
 160
 161 static struct platform_driver serial8250_em_platform_driver = {
 162         .driver = {
 163                 .name           = "serial8250-em",
 164                 .of_match_table = serial8250_em_dt_ids,
 165                 .owner          = THIS_MODULE,
 166         },
 167         .probe                  = serial8250_em_probe,
 168         .remove                 = serial8250_em_remove,
 169 };
 170
 171 module_platform_driver(serial8250_em_platform_driver);
 172
 173 MODULE_AUTHOR("Magnus Damm");
 174 MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
 175 MODULE_LICENSE("GPL v2");