arch/arm/mach-davinci/serial.c

   1 /*
   2  * TI DaVinci serial driver
   3  *
   4  * Copyright (C) 2006 Texas Instruments.
   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  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  *
  20  */
  21
  22 #include <linux/kernel.h>
  23 #include <linux/init.h>
  24 #include <linux/serial_8250.h>
  25 #include <linux/serial_reg.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/delay.h>
  28 #include <linux/clk.h>
  29 #include <linux/io.h>
  30
  31 #include <mach/serial.h>
  32 #include <mach/cputype.h>
  33
  34 static inline unsigned int serial_read_reg(struct plat_serial8250_port *up,
  35                                            int offset)
  36 {
  37         offset <<= up->regshift;
  38         return (unsigned int)__raw_readl(IO_ADDRESS(up->mapbase) + offset);
  39 }
  40
  41 static inline void serial_write_reg(struct plat_serial8250_port *p, int offset,
  42                                     int value)
  43 {
  44         offset <<= p->regshift;
  45         __raw_writel(value, IO_ADDRESS(p->mapbase) + offset);
  46 }
  47
  48 static void __init davinci_serial_reset(struct plat_serial8250_port *p)
  49 {
  50         unsigned int pwremu = 0;
  51
  52         serial_write_reg(p, UART_IER, 0);  /* disable all interrupts */
  53
  54         /* reset both transmitter and receiver: bits 14,13 = UTRST, URRST */
  55         serial_write_reg(p, UART_DAVINCI_PWREMU, pwremu);
  56         mdelay(10);
  57
  58         pwremu |= (0x3 << 13);
  59         pwremu |= 0x1;
  60         serial_write_reg(p, UART_DAVINCI_PWREMU, pwremu);
  61
  62         if (cpu_is_davinci_dm646x())
  63                 serial_write_reg(p, UART_DM646X_SCR,
  64                                  UART_DM646X_SCR_TX_WATERMARK);
  65 }
  66
  67 int __init davinci_serial_init(struct davinci_uart_config *info)
  68 {
  69         int i;
  70         char name[16];
  71         struct clk *uart_clk;
  72         struct davinci_soc_info *soc_info = &davinci_soc_info;
  73         struct device *dev = &soc_info->serial_dev->dev;
  74         struct plat_serial8250_port *p = dev->platform_data;
  75
  76         /*
  77          * Make sure the serial ports are muxed on at this point.
  78          * You have to mux them off in device drivers later on if not needed.
  79          */
  80         for (i = 0; i < DAVINCI_MAX_NR_UARTS; i++, p++) {
  81                 if (!(info->enabled_uarts & (1 << i)))
  82                         continue;
  83
  84                 sprintf(name, "uart%d", i);
  85                 uart_clk = clk_get(dev, name);
  86                 if (IS_ERR(uart_clk))
  87                         printk(KERN_ERR "%s:%d: failed to get UART%d clock\n",
  88                                         __func__, __LINE__, i);
  89                 else {
  90                         clk_enable(uart_clk);
  91                         p->uartclk = clk_get_rate(uart_clk);
  92                         davinci_serial_reset(p);
  93                 }
  94         }
  95
  96         return platform_device_register(soc_info->serial_dev);
  97 }