drivers/serial/serial_s5p.c

   1 /*
   2  * (C) Copyright 2009 SAMSUNG Electronics
   3  * Minkyu Kang <mk7.kang@samsung.com>
   4  * Heungjun Kim <riverful.kim@samsung.com>
   5  *
   6  * based on drivers/serial/s3c64xx.c
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  *
  22  */
  23
  24 #include <common.h>
  25 #include <linux/compiler.h>
  26 #include <asm/io.h>
  27 #include <asm/arch/uart.h>
  28 #include <asm/arch/clk.h>
  29 #include <serial.h>
  30
  31 DECLARE_GLOBAL_DATA_PTR;
  32
  33 static inline struct s5p_uart *s5p_get_base_uart(int dev_index)
  34 {
  35         u32 offset = dev_index * sizeof(struct s5p_uart);
  36         return (struct s5p_uart *)(samsung_get_base_uart() + offset);
  37 }
  38
  39 /*
  40  * The coefficient, used to calculate the baudrate on S5P UARTs is
  41  * calculated as
  42  * C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT
  43  * however, section 31.6.11 of the datasheet doesn't recomment using 1 for 1,
  44  * 3 for 2, ... (2^n - 1) for n, instead, they suggest using these constants:
  45  */
  46 static const int udivslot[] = {
  47         0,
  48         0x0080,
  49         0x0808,
  50         0x0888,
  51         0x2222,
  52         0x4924,
  53         0x4a52,
  54         0x54aa,
  55         0x5555,
  56         0xd555,
  57         0xd5d5,
  58         0xddd5,
  59         0xdddd,
  60         0xdfdd,
  61         0xdfdf,
  62         0xffdf,
  63 };
  64
  65 void serial_setbrg_dev(const int dev_index)
  66 {
  67         struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
  68         u32 uclk = get_uart_clk(dev_index);
  69         u32 baudrate = gd->baudrate;
  70         u32 val;
  71
  72         val = uclk / baudrate;
  73
  74         writel(val / 16 - 1, &uart->ubrdiv);
  75
  76         if (s5p_uart_divslot())
  77                 writew(udivslot[val % 16], &uart->rest.slot);
  78         else
  79                 writeb(val % 16, &uart->rest.value);
  80 }
  81
  82 /*
  83  * Initialise the serial port with the given baudrate. The settings
  84  * are always 8 data bits, no parity, 1 stop bit, no start bits.
  85  */
  86 int serial_init_dev(const int dev_index)
  87 {
  88         struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
  89
  90         /* reset and enable FIFOs, set triggers to the maximum */
  91         writel(0, &uart->ufcon);
  92         writel(0, &uart->umcon);
  93         /* 8N1 */
  94         writel(0x3, &uart->ulcon);
  95         /* No interrupts, no DMA, pure polling */
  96         writel(0x245, &uart->ucon);
  97
  98         serial_setbrg_dev(dev_index);
  99
 100         return 0;
 101 }
 102
 103 static int serial_err_check(const int dev_index, int op)
 104 {
 105         struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
 106         unsigned int mask;
 107
 108         /*
 109          * UERSTAT
 110          * Break Detect [3]
 111          * Frame Err    [2] : receive operation
 112          * Parity Err   [1] : receive operation
 113          * Overrun Err  [0] : receive operation
 114          */
 115         if (op)
 116                 mask = 0x8;
 117         else
 118                 mask = 0xf;
 119
 120         return readl(&uart->uerstat) & mask;
 121 }
 122
 123 /*
 124  * Read a single byte from the serial port. Returns 1 on success, 0
 125  * otherwise. When the function is succesfull, the character read is
 126  * written into its argument c.
 127  */
 128 int serial_getc_dev(const int dev_index)
 129 {
 130         struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
 131
 132         /* wait for character to arrive */
 133         while (!(readl(&uart->utrstat) & 0x1)) {
 134                 if (serial_err_check(dev_index, 0))
 135                         return 0;
 136         }
 137
 138         return (int)(readb(&uart->urxh) & 0xff);
 139 }
 140
 141 /*
 142  * Output a single byte to the serial port.
 143  */
 144 void serial_putc_dev(const char c, const int dev_index)
 145 {
 146         struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
 147
 148         /* wait for room in the tx FIFO */
 149         while (!(readl(&uart->utrstat) & 0x2)) {
 150                 if (serial_err_check(dev_index, 1))
 151                         return;
 152         }
 153
 154         writeb(c, &uart->utxh);
 155
 156         /* If \n, also do \r */
 157         if (c == '\n')
 158                 serial_putc('\r');
 159 }
 160
 161 /*
 162  * Test whether a character is in the RX buffer
 163  */
 164 int serial_tstc_dev(const int dev_index)
 165 {
 166         struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
 167
 168         return (int)(readl(&uart->utrstat) & 0x1);
 169 }
 170
 171 void serial_puts_dev(const char *s, const int dev_index)
 172 {
 173         while (*s)
 174                 serial_putc_dev(*s++, dev_index);
 175 }
 176
 177 /* Multi serial device functions */
 178 #define DECLARE_S5P_SERIAL_FUNCTIONS(port) \
 179 int s5p_serial##port##_init(void) { return serial_init_dev(port); } \
 180 void s5p_serial##port##_setbrg(void) { serial_setbrg_dev(port); } \
 181 int s5p_serial##port##_getc(void) { return serial_getc_dev(port); } \
 182 int s5p_serial##port##_tstc(void) { return serial_tstc_dev(port); } \
 183 void s5p_serial##port##_putc(const char c) { serial_putc_dev(c, port); } \
 184 void s5p_serial##port##_puts(const char *s) { serial_puts_dev(s, port); }
 185
 186 #define INIT_S5P_SERIAL_STRUCTURE(port, __name) {       \
 187         .name   = __name,                               \
 188         .start  = s5p_serial##port##_init,              \
 189         .stop   = NULL,                                 \
 190         .setbrg = s5p_serial##port##_setbrg,            \
 191         .getc   = s5p_serial##port##_getc,              \
 192         .tstc   = s5p_serial##port##_tstc,              \
 193         .putc   = s5p_serial##port##_putc,              \
 194         .puts   = s5p_serial##port##_puts,              \
 195 }
 196
 197 DECLARE_S5P_SERIAL_FUNCTIONS(0);
 198 struct serial_device s5p_serial0_device =
 199         INIT_S5P_SERIAL_STRUCTURE(0, "s5pser0");
 200 DECLARE_S5P_SERIAL_FUNCTIONS(1);
 201 struct serial_device s5p_serial1_device =
 202         INIT_S5P_SERIAL_STRUCTURE(1, "s5pser1");
 203 DECLARE_S5P_SERIAL_FUNCTIONS(2);
 204 struct serial_device s5p_serial2_device =
 205         INIT_S5P_SERIAL_STRUCTURE(2, "s5pser2");
 206 DECLARE_S5P_SERIAL_FUNCTIONS(3);
 207 struct serial_device s5p_serial3_device =
 208         INIT_S5P_SERIAL_STRUCTURE(3, "s5pser3");
 209
 210 __weak struct serial_device *default_serial_console(void)
 211 {
 212 #if defined(CONFIG_SERIAL0)
 213         return &s5p_serial0_device;
 214 #elif defined(CONFIG_SERIAL1)
 215         return &s5p_serial1_device;
 216 #elif defined(CONFIG_SERIAL2)
 217         return &s5p_serial2_device;
 218 #elif defined(CONFIG_SERIAL3)
 219         return &s5p_serial3_device;
 220 #else
 221 #error "CONFIG_SERIAL? missing."
 222 #endif
 223 }
 224
 225 void s5p_serial_initialize(void)
 226 {
 227         serial_register(&s5p_serial0_device);
 228         serial_register(&s5p_serial1_device);
 229         serial_register(&s5p_serial2_device);
 230         serial_register(&s5p_serial3_device);
 231 }