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  * SPDX-License-Identifier:     GPL-2.0+
   9  */
  10
  11 #include <common.h>
  12 #include <dm.h>
  13 #include <errno.h>
  14 #include <fdtdec.h>
  15 #include <linux/compiler.h>
  16 #include <asm/io.h>
  17 #include <asm/arch/clk.h>
  18 #include <asm/arch/uart.h>
  19 #include <serial.h>
  20
  21 DECLARE_GLOBAL_DATA_PTR;
  22
  23 #define RX_FIFO_COUNT_SHIFT     0
  24 #define RX_FIFO_COUNT_MASK      (0xff << RX_FIFO_COUNT_SHIFT)
  25 #define RX_FIFO_FULL            (1 << 8)
  26 #define TX_FIFO_COUNT_SHIFT     16
  27 #define TX_FIFO_COUNT_MASK      (0xff << TX_FIFO_COUNT_SHIFT)
  28 #define TX_FIFO_FULL            (1 << 24)
  29
  30 /* Information about a serial port */
  31 struct s5p_serial_platdata {
  32         struct s5p_uart *reg;  /* address of registers in physical memory */
  33         u8 port_id;     /* uart port number */
  34 };
  35
  36 /*
  37  * The coefficient, used to calculate the baudrate on S5P UARTs is
  38  * calculated as
  39  * C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT
  40  * however, section 31.6.11 of the datasheet doesn't recomment using 1 for 1,
  41  * 3 for 2, ... (2^n - 1) for n, instead, they suggest using these constants:
  42  */
  43 static const int udivslot[] = {
  44         0,
  45         0x0080,
  46         0x0808,
  47         0x0888,
  48         0x2222,
  49         0x4924,
  50         0x4a52,
  51         0x54aa,
  52         0x5555,
  53         0xd555,
  54         0xd5d5,
  55         0xddd5,
  56         0xdddd,
  57         0xdfdd,
  58         0xdfdf,
  59         0xffdf,
  60 };
  61
  62 static void __maybe_unused s5p_serial_init(struct s5p_uart *uart)
  63 {
  64         /* enable FIFOs, auto clear Rx FIFO */
  65         writel(0x3, &uart->ufcon);
  66         writel(0, &uart->umcon);
  67         /* 8N1 */
  68         writel(0x3, &uart->ulcon);
  69         /* No interrupts, no DMA, pure polling */
  70         writel(0x245, &uart->ucon);
  71 }
  72
  73 static void __maybe_unused s5p_serial_baud(struct s5p_uart *uart, uint uclk,
  74                                            int baudrate)
  75 {
  76         u32 val;
  77
  78         val = uclk / baudrate;
  79
  80         writel(val / 16 - 1, &uart->ubrdiv);
  81
  82         if (s5p_uart_divslot())
  83                 writew(udivslot[val % 16], &uart->rest.slot);
  84         else
  85                 writeb(val % 16, &uart->rest.value);
  86 }
  87
  88 int s5p_serial_setbrg(struct udevice *dev, int baudrate)
  89 {
  90         struct s5p_serial_platdata *plat = dev->platdata;
  91         struct s5p_uart *const uart = plat->reg;
  92         u32 uclk = get_uart_clk(plat->port_id);
  93
  94         s5p_serial_baud(uart, uclk, baudrate);
  95
  96         return 0;
  97 }
  98
  99 static int s5p_serial_probe(struct udevice *dev)
 100 {
 101         struct s5p_serial_platdata *plat = dev->platdata;
 102         struct s5p_uart *const uart = plat->reg;
 103
 104         s5p_serial_init(uart);
 105
 106         return 0;
 107 }
 108
 109 static int serial_err_check(const struct s5p_uart *const uart, int op)
 110 {
 111         unsigned int mask;
 112
 113         /*
 114          * UERSTAT
 115          * Break Detect [3]
 116          * Frame Err    [2] : receive operation
 117          * Parity Err   [1] : receive operation
 118          * Overrun Err  [0] : receive operation
 119          */
 120         if (op)
 121                 mask = 0x8;
 122         else
 123                 mask = 0xf;
 124
 125         return readl(&uart->uerstat) & mask;
 126 }
 127
 128 static int s5p_serial_getc(struct udevice *dev)
 129 {
 130         struct s5p_serial_platdata *plat = dev->platdata;
 131         struct s5p_uart *const uart = plat->reg;
 132
 133         if (!(readl(&uart->ufstat) & RX_FIFO_COUNT_MASK))
 134                 return -EAGAIN;
 135
 136         serial_err_check(uart, 0);
 137         return (int)(readb(&uart->urxh) & 0xff);
 138 }
 139
 140 static int s5p_serial_putc(struct udevice *dev, const char ch)
 141 {
 142         struct s5p_serial_platdata *plat = dev->platdata;
 143         struct s5p_uart *const uart = plat->reg;
 144
 145         if (readl(&uart->ufstat) & TX_FIFO_FULL)
 146                 return -EAGAIN;
 147
 148         writeb(ch, &uart->utxh);
 149         serial_err_check(uart, 1);
 150
 151         return 0;
 152 }
 153
 154 static int s5p_serial_pending(struct udevice *dev, bool input)
 155 {
 156         struct s5p_serial_platdata *plat = dev->platdata;
 157         struct s5p_uart *const uart = plat->reg;
 158         uint32_t ufstat = readl(&uart->ufstat);
 159
 160         if (input)
 161                 return (ufstat & RX_FIFO_COUNT_MASK) >> RX_FIFO_COUNT_SHIFT;
 162         else
 163                 return (ufstat & TX_FIFO_COUNT_MASK) >> TX_FIFO_COUNT_SHIFT;
 164 }
 165
 166 static int s5p_serial_ofdata_to_platdata(struct udevice *dev)
 167 {
 168         struct s5p_serial_platdata *plat = dev->platdata;
 169         fdt_addr_t addr;
 170
 171         addr = fdtdec_get_addr(gd->fdt_blob, dev->of_offset, "reg");
 172         if (addr == FDT_ADDR_T_NONE)
 173                 return -EINVAL;
 174
 175         plat->reg = (struct s5p_uart *)addr;
 176         plat->port_id = fdtdec_get_int(gd->fdt_blob, dev->of_offset, "id", -1);
 177
 178         return 0;
 179 }
 180
 181 static const struct dm_serial_ops s5p_serial_ops = {
 182         .putc = s5p_serial_putc,
 183         .pending = s5p_serial_pending,
 184         .getc = s5p_serial_getc,
 185         .setbrg = s5p_serial_setbrg,
 186 };
 187
 188 static const struct udevice_id s5p_serial_ids[] = {
 189         { .compatible = "samsung,exynos4210-uart" },
 190         { }
 191 };
 192
 193 U_BOOT_DRIVER(serial_s5p) = {
 194         .name   = "serial_s5p",
 195         .id     = UCLASS_SERIAL,
 196         .of_match = s5p_serial_ids,
 197         .ofdata_to_platdata = s5p_serial_ofdata_to_platdata,
 198         .platdata_auto_alloc_size = sizeof(struct s5p_serial_platdata),
 199         .probe = s5p_serial_probe,
 200         .ops    = &s5p_serial_ops,
 201         .flags = DM_FLAG_PRE_RELOC,
 202 };
 203
 204 #ifdef CONFIG_DEBUG_UART_S5P
 205
 206 #include <debug_uart.h>
 207
 208 void debug_uart_init(void)
 209 {
 210         struct s5p_uart *uart = (struct s5p_uart *)CONFIG_DEBUG_UART_BASE;
 211
 212         s5p_serial_init(uart);
 213         s5p_serial_baud(uart, CONFIG_DEBUG_UART_CLOCK, CONFIG_BAUDRATE);
 214 }
 215
 216 static inline void _debug_uart_putc(int ch)
 217 {
 218         struct s5p_uart *uart = (struct s5p_uart *)CONFIG_DEBUG_UART_BASE;
 219
 220         while (readl(&uart->ufstat) & TX_FIFO_FULL);
 221
 222         writeb(ch, &uart->utxh);
 223 }
 224
 225 DEBUG_UART_FUNCS
 226
 227 #endif