drivers/serial/serial_meson.c

   1 /*
   2  * (C) Copyright 2016 Beniamino Galvani <b.galvani@gmail.com>
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 #include <common.h>
   8 #include <dm.h>
   9 #include <errno.h>
  10 #include <fdtdec.h>
  11 #include <linux/compiler.h>
  12 #include <serial.h>
  13
  14 DECLARE_GLOBAL_DATA_PTR;
  15
  16 struct meson_uart {
  17         u32 wfifo;
  18         u32 rfifo;
  19         u32 control;
  20         u32 status;
  21         u32 misc;
  22 };
  23
  24 struct meson_serial_platdata {
  25         struct meson_uart *reg;
  26 };
  27
  28 /* AML_UART_STATUS bits */
  29 #define AML_UART_PARITY_ERR             BIT(16)
  30 #define AML_UART_FRAME_ERR              BIT(17)
  31 #define AML_UART_TX_FIFO_WERR           BIT(18)
  32 #define AML_UART_RX_EMPTY               BIT(20)
  33 #define AML_UART_TX_FULL                BIT(21)
  34 #define AML_UART_TX_EMPTY               BIT(22)
  35 #define AML_UART_XMIT_BUSY              BIT(25)
  36 #define AML_UART_ERR                    (AML_UART_PARITY_ERR | \
  37                                          AML_UART_FRAME_ERR  | \
  38                                          AML_UART_TX_FIFO_WERR)
  39
  40 /* AML_UART_CONTROL bits */
  41 #define AML_UART_TX_EN                  BIT(12)
  42 #define AML_UART_RX_EN                  BIT(13)
  43 #define AML_UART_TX_RST                 BIT(22)
  44 #define AML_UART_RX_RST                 BIT(23)
  45 #define AML_UART_CLR_ERR                BIT(24)
  46
  47 static void meson_serial_init(struct meson_uart *uart)
  48 {
  49         u32 val;
  50
  51         val = readl(&uart->control);
  52         val |= (AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR);
  53         writel(val, &uart->control);
  54         val &= ~(AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR);
  55         writel(val, &uart->control);
  56         val |= (AML_UART_RX_EN | AML_UART_TX_EN);
  57         writel(val, &uart->control);
  58 }
  59
  60 static int meson_serial_probe(struct udevice *dev)
  61 {
  62         struct meson_serial_platdata *plat = dev->platdata;
  63         struct meson_uart *const uart = plat->reg;
  64
  65         meson_serial_init(uart);
  66
  67         return 0;
  68 }
  69
  70 static int meson_serial_getc(struct udevice *dev)
  71 {
  72         struct meson_serial_platdata *plat = dev->platdata;
  73         struct meson_uart *const uart = plat->reg;
  74
  75         if (readl(&uart->status) & AML_UART_RX_EMPTY)
  76                 return -EAGAIN;
  77
  78         return readl(&uart->rfifo) & 0xff;
  79 }
  80
  81 static int meson_serial_putc(struct udevice *dev, const char ch)
  82 {
  83         struct meson_serial_platdata *plat = dev->platdata;
  84         struct meson_uart *const uart = plat->reg;
  85
  86         if (readl(&uart->status) & AML_UART_TX_FULL)
  87                 return -EAGAIN;
  88
  89         writel(ch, &uart->wfifo);
  90
  91         return 0;
  92 }
  93
  94 static int meson_serial_pending(struct udevice *dev, bool input)
  95 {
  96         struct meson_serial_platdata *plat = dev->platdata;
  97         struct meson_uart *const uart = plat->reg;
  98         uint32_t status = readl(&uart->status);
  99
 100         if (input)
 101                 return !(status & AML_UART_RX_EMPTY);
 102         else
 103                 return !(status & AML_UART_TX_FULL);
 104 }
 105
 106 static int meson_serial_ofdata_to_platdata(struct udevice *dev)
 107 {
 108         struct meson_serial_platdata *plat = dev->platdata;
 109         fdt_addr_t addr;
 110
 111         addr = devfdt_get_addr(dev);
 112         if (addr == FDT_ADDR_T_NONE)
 113                 return -EINVAL;
 114
 115         plat->reg = (struct meson_uart *)addr;
 116
 117         return 0;
 118 }
 119
 120 static const struct dm_serial_ops meson_serial_ops = {
 121         .putc = meson_serial_putc,
 122         .pending = meson_serial_pending,
 123         .getc = meson_serial_getc,
 124 };
 125
 126 static const struct udevice_id meson_serial_ids[] = {
 127         { .compatible = "amlogic,meson-uart" },
 128         { }
 129 };
 130
 131 U_BOOT_DRIVER(serial_meson) = {
 132         .name           = "serial_meson",
 133         .id             = UCLASS_SERIAL,
 134         .of_match       = meson_serial_ids,
 135         .probe          = meson_serial_probe,
 136         .ops            = &meson_serial_ops,
 137         .flags          = DM_FLAG_PRE_RELOC,
 138         .ofdata_to_platdata = meson_serial_ofdata_to_platdata,
 139         .platdata_auto_alloc_size = sizeof(struct meson_serial_platdata),
 140 };
 141
 142 #ifdef CONFIG_DEBUG_UART_MESON
 143
 144 #include <debug_uart.h>
 145
 146 static inline void _debug_uart_init(void)
 147 {
 148 }
 149
 150 static inline void _debug_uart_putc(int ch)
 151 {
 152         struct meson_uart *regs = (struct meson_uart *)CONFIG_DEBUG_UART_BASE;
 153
 154         while (readl(&regs->status) & AML_UART_TX_FULL)
 155                 ;
 156
 157         writel(ch, &regs->wfifo);
 158 }
 159
 160 DEBUG_UART_FUNCS
 161
 162 #endif