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 <asm/irq.h>
  32 #include <mach/hardware.h>
  33 #include <mach/serial.h>
  34 #include <mach/irqs.h>
  35 #include <mach/cputype.h>
  36 #include <mach/common.h>
  37
  38 #include "clock.h"
  39
  40 static inline unsigned int serial_read_reg(struct plat_serial8250_port *up,
  41                                            int offset)
  42 {
  43         offset <<= up->regshift;
  44         return (unsigned int)__raw_readl(IO_ADDRESS(up->mapbase) + offset);
  45 }
  46
  47 static inline void serial_write_reg(struct plat_serial8250_port *p, int offset,
  48                                     int value)
  49 {
  50         offset <<= p->regshift;
  51         __raw_writel(value, IO_ADDRESS(p->mapbase) + offset);
  52 }
  53
  54 static void __init davinci_serial_reset(struct plat_serial8250_port *p)
  55 {
  56         unsigned int pwremu = 0;
  57
  58         serial_write_reg(p, UART_IER, 0);  /* disable all interrupts */
  59
  60         /* reset both transmitter and receiver: bits 14,13 = UTRST, URRST */
  61         serial_write_reg(p, UART_DAVINCI_PWREMU, pwremu);
  62         mdelay(10);
  63
  64         pwremu |= (0x3 << 13);
  65         pwremu |= 0x1;
  66         serial_write_reg(p, UART_DAVINCI_PWREMU, pwremu);
  67
  68         if (cpu_is_davinci_dm646x())
  69                 serial_write_reg(p, UART_DM646X_SCR,
  70                                  UART_DM646X_SCR_TX_WATERMARK);
  71 }
  72
  73 int __init davinci_serial_init(struct davinci_uart_config *info)
  74 {
  75         int i;
  76         char name[16];
  77         struct clk *uart_clk;
  78         struct davinci_soc_info *soc_info = &davinci_soc_info;
  79         struct device *dev = &soc_info->serial_dev->dev;
  80         struct plat_serial8250_port *p = dev->platform_data;
  81
  82         /*
  83          * Make sure the serial ports are muxed on at this point.
  84          * You have to mux them off in device drivers later on if not needed.
  85          */
  86         for (i = 0; i < DAVINCI_MAX_NR_UARTS; i++, p++) {
  87                 if (!(info->enabled_uarts & (1 << i)))
  88                         continue;
  89
  90                 sprintf(name, "uart%d", i);
  91                 uart_clk = clk_get(dev, name);
  92                 if (IS_ERR(uart_clk))
  93                         printk(KERN_ERR "%s:%d: failed to get UART%d clock\n",
  94                                         __func__, __LINE__, i);
  95                 else {
  96                         clk_enable(uart_clk);
  97                         p->uartclk = clk_get_rate(uart_clk);
  98                         davinci_serial_reset(p);
  99                 }
 100         }
 101
 102         return platform_device_register(soc_info->serial_dev);
 103 }