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
  39         WARN_ONCE(!up->membase, "unmapped read: uart[%d]\n", offset);
  40
  41         return (unsigned int)__raw_readl(up->membase + offset);
  42 }
  43
  44 static inline void serial_write_reg(struct plat_serial8250_port *p, int offset,
  45                                     int value)
  46 {
  47         offset <<= p->regshift;
  48
  49         WARN_ONCE(!p->membase, "unmapped write: uart[%d]\n", offset);
  50
  51         __raw_writel(value, p->membase + 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 /* Enable UART clock and obtain its rate */
  74 int __init davinci_serial_setup_clk(unsigned instance, unsigned int *rate)
  75 {
  76         char name[16];
  77         struct clk *clk;
  78         struct davinci_soc_info *soc_info = &davinci_soc_info;
  79         struct device *dev = &soc_info->serial_dev->dev;
  80
  81         sprintf(name, "uart%d", instance);
  82         clk = clk_get(dev, name);
  83         if (IS_ERR(clk)) {
  84                 pr_err("%s:%d: failed to get UART%d clock\n",
  85                                         __func__, __LINE__, instance);
  86                 return PTR_ERR(clk);
  87         }
  88
  89         clk_prepare_enable(clk);
  90
  91         if (rate)
  92                 *rate = clk_get_rate(clk);
  93
  94         return 0;
  95 }
  96
  97 int __init davinci_serial_init(struct davinci_uart_config *info)
  98 {
  99         int i, ret;
 100         struct davinci_soc_info *soc_info = &davinci_soc_info;
 101         struct device *dev = &soc_info->serial_dev->dev;
 102         struct plat_serial8250_port *p = dev->platform_data;
 103
 104         /*
 105          * Make sure the serial ports are muxed on at this point.
 106          * You have to mux them off in device drivers later on if not needed.
 107          */
 108         for (i = 0; p->flags; i++, p++) {
 109                 if (!(info->enabled_uarts & (1 << i)))
 110                         continue;
 111
 112                 ret = davinci_serial_setup_clk(i, &p->uartclk);
 113                 if (ret)
 114                         continue;
 115
 116                 if (!p->membase && p->mapbase) {
 117                         p->membase = ioremap(p->mapbase, SZ_4K);
 118
 119                         if (p->membase)
 120                                 p->flags &= ~UPF_IOREMAP;
 121                         else
 122                                 pr_err("uart regs ioremap failed\n");
 123                 }
 124
 125                 if (p->membase && p->type != PORT_AR7)
 126                         davinci_serial_reset(p);
 127         }
 128
 129         return platform_device_register(soc_info->serial_dev);
 130 }