drivers/tty/serial/8250/8250_dw.c

   1 /*
   2  * Synopsys DesignWare 8250 driver.
   3  *
   4  * Copyright 2011 Picochip, Jamie Iles.
   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, or
   9  * (at your option) any later version.
  10  *
  11  * The Synopsys DesignWare 8250 has an extra feature whereby it detects if the
  12  * LCR is written whilst busy.  If it is, then a busy detect interrupt is
  13  * raised, the LCR needs to be rewritten and the uart status register read.
  14  */
  15 #include <linux/device.h>
  16 #include <linux/init.h>
  17 #include <linux/io.h>
  18 #include <linux/module.h>
  19 #include <linux/serial_8250.h>
  20 #include <linux/serial_core.h>
  21 #include <linux/serial_reg.h>
  22 #include <linux/of.h>
  23 #include <linux/of_irq.h>
  24 #include <linux/of_platform.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/slab.h>
  27
  28 struct dw8250_data {
  29         int     last_lcr;
  30         int     line;
  31 };
  32
  33 static void dw8250_serial_out(struct uart_port *p, int offset, int value)
  34 {
  35         struct dw8250_data *d = p->private_data;
  36
  37         if (offset == UART_LCR)
  38                 d->last_lcr = value;
  39
  40         offset <<= p->regshift;
  41         writeb(value, p->membase + offset);
  42 }
  43
  44 static unsigned int dw8250_serial_in(struct uart_port *p, int offset)
  45 {
  46         offset <<= p->regshift;
  47
  48         return readb(p->membase + offset);
  49 }
  50
  51 static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
  52 {
  53         struct dw8250_data *d = p->private_data;
  54
  55         if (offset == UART_LCR)
  56                 d->last_lcr = value;
  57
  58         offset <<= p->regshift;
  59         writel(value, p->membase + offset);
  60 }
  61
  62 static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
  63 {
  64         offset <<= p->regshift;
  65
  66         return readl(p->membase + offset);
  67 }
  68
  69 /* Offset for the DesignWare's UART Status Register. */
  70 #define UART_USR        0x1f
  71
  72 static int dw8250_handle_irq(struct uart_port *p)
  73 {
  74         struct dw8250_data *d = p->private_data;
  75         unsigned int iir = p->serial_in(p, UART_IIR);
  76
  77         if (serial8250_handle_irq(p, iir)) {
  78                 return 1;
  79         } else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
  80                 /* Clear the USR and write the LCR again. */
  81                 (void)p->serial_in(p, UART_USR);
  82                 p->serial_out(p, d->last_lcr, UART_LCR);
  83
  84                 return 1;
  85         }
  86
  87         return 0;
  88 }
  89
  90 static int __devinit dw8250_probe(struct platform_device *pdev)
  91 {
  92         struct uart_port port = {};
  93         struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  94         struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  95         struct device_node *np = pdev->dev.of_node;
  96         u32 val;
  97         struct dw8250_data *data;
  98
  99         if (!regs || !irq) {
 100                 dev_err(&pdev->dev, "no registers/irq defined\n");
 101                 return -EINVAL;
 102         }
 103
 104         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 105         if (!data)
 106                 return -ENOMEM;
 107         port.private_data = data;
 108
 109         spin_lock_init(&port.lock);
 110         port.mapbase = regs->start;
 111         port.irq = irq->start;
 112         port.handle_irq = dw8250_handle_irq;
 113         port.type = PORT_8250;
 114         port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP |
 115                 UPF_FIXED_PORT | UPF_FIXED_TYPE;
 116         port.dev = &pdev->dev;
 117
 118         port.iotype = UPIO_MEM;
 119         port.serial_in = dw8250_serial_in;
 120         port.serial_out = dw8250_serial_out;
 121         if (!of_property_read_u32(np, "reg-io-width", &val)) {
 122                 switch (val) {
 123                 case 1:
 124                         break;
 125                 case 4:
 126                         port.iotype = UPIO_MEM32;
 127                         port.serial_in = dw8250_serial_in32;
 128                         port.serial_out = dw8250_serial_out32;
 129                         break;
 130                 default:
 131                         dev_err(&pdev->dev, "unsupported reg-io-width (%u)\n",
 132                                 val);
 133                         return -EINVAL;
 134                 }
 135         }
 136
 137         if (!of_property_read_u32(np, "reg-shift", &val))
 138                 port.regshift = val;
 139
 140         if (of_property_read_u32(np, "clock-frequency", &val)) {
 141                 dev_err(&pdev->dev, "no clock-frequency property set\n");
 142                 return -EINVAL;
 143         }
 144         port.uartclk = val;
 145
 146         data->line = serial8250_register_port(&port);
 147         if (data->line < 0)
 148                 return data->line;
 149
 150         platform_set_drvdata(pdev, data);
 151
 152         return 0;
 153 }
 154
 155 static int __devexit dw8250_remove(struct platform_device *pdev)
 156 {
 157         struct dw8250_data *data = platform_get_drvdata(pdev);
 158
 159         serial8250_unregister_port(data->line);
 160
 161         return 0;
 162 }
 163
 164 static const struct of_device_id dw8250_match[] = {
 165         { .compatible = "snps,dw-apb-uart" },
 166         { /* Sentinel */ }
 167 };
 168 MODULE_DEVICE_TABLE(of, dw8250_match);
 169
 170 static struct platform_driver dw8250_platform_driver = {
 171         .driver = {
 172                 .name           = "dw-apb-uart",
 173                 .owner          = THIS_MODULE,
 174                 .of_match_table = dw8250_match,
 175         },
 176         .probe                  = dw8250_probe,
 177         .remove                 = __devexit_p(dw8250_remove),
 178 };
 179
 180 module_platform_driver(dw8250_platform_driver);
 181
 182 MODULE_AUTHOR("Jamie Iles");
 183 MODULE_LICENSE("GPL");
 184 MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver");