drivers/serial/serial_owl.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Actions Semi OWL SoCs UART driver
   4  *
   5  * Copyright (C) 2015 Actions Semi Co., Ltd.
   6  * Copyright (C) 2018 Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
   7  */
   8
   9 #include <common.h>
  10 #include <clk.h>
  11 #include <dm.h>
  12 #include <errno.h>
  13 #include <fdtdec.h>
  14 #include <serial.h>
  15 #include <asm/io.h>
  16 #include <asm/types.h>
  17
  18 /* UART Registers */
  19 #define OWL_UART_CTL                    (0x0000)
  20 #define OWL_UART_RXDAT                  (0x0004)
  21 #define OWL_UART_TXDAT                  (0x0008)
  22 #define OWL_UART_STAT                   (0x000C)
  23
  24 /* UART_CTL Register Definitions */
  25 #define OWL_UART_CTL_PRS_NONE           GENMASK(6, 4)
  26 #define OWL_UART_CTL_STPS               BIT(2)
  27 #define OWL_UART_CTL_DWLS               3
  28
  29 /* UART_STAT Register Definitions */
  30 #define OWL_UART_STAT_TFES              BIT(10) /* TX FIFO Empty Status */
  31 #define OWL_UART_STAT_RFFS              BIT(9)  /* RX FIFO full Status */
  32 #define OWL_UART_STAT_TFFU              BIT(6)  /* TX FIFO full Status */
  33 #define OWL_UART_STAT_RFEM              BIT(5)  /* RX FIFO Empty Status */
  34
  35 struct owl_serial_priv {
  36         phys_addr_t base;
  37 };
  38
  39 int owl_serial_setbrg(struct udevice *dev, int baudrate)
  40 {
  41         /* Driver supports only fixed baudrate */
  42         return 0;
  43 }
  44
  45 static int owl_serial_getc(struct udevice *dev)
  46 {
  47         struct owl_serial_priv *priv = dev_get_priv(dev);
  48
  49         if (readl(priv->base + OWL_UART_STAT) & OWL_UART_STAT_RFEM)
  50                 return -EAGAIN;
  51
  52         return (int)(readl(priv->base + OWL_UART_RXDAT));
  53 }
  54
  55 static int owl_serial_putc(struct udevice *dev, const char ch)
  56 {
  57         struct owl_serial_priv *priv = dev_get_priv(dev);
  58
  59         if (readl(priv->base + OWL_UART_STAT) & OWL_UART_STAT_TFFU)
  60                 return -EAGAIN;
  61
  62         writel(ch, priv->base + OWL_UART_TXDAT);
  63
  64         return 0;
  65 }
  66
  67 static int owl_serial_pending(struct udevice *dev, bool input)
  68 {
  69         struct owl_serial_priv *priv = dev_get_priv(dev);
  70         unsigned int stat = readl(priv->base + OWL_UART_STAT);
  71
  72         if (input)
  73                 return !(stat & OWL_UART_STAT_RFEM);
  74         else
  75                 return !(stat & OWL_UART_STAT_TFES);
  76 }
  77
  78 static int owl_serial_probe(struct udevice *dev)
  79 {
  80         struct owl_serial_priv *priv = dev_get_priv(dev);
  81         struct clk clk;
  82         u32 uart_ctl;
  83         int ret;
  84
  85         /* Set data, parity and stop bits */
  86         uart_ctl = readl(priv->base + OWL_UART_CTL);
  87         uart_ctl &= ~(OWL_UART_CTL_PRS_NONE);
  88         uart_ctl &= ~(OWL_UART_CTL_STPS);
  89         uart_ctl |= OWL_UART_CTL_DWLS;
  90         writel(uart_ctl, priv->base + OWL_UART_CTL);
  91
  92         /* Enable UART clock */
  93         ret = clk_get_by_index(dev, 0, &clk);
  94         if (ret < 0)
  95                 return ret;
  96
  97         ret = clk_enable(&clk);
  98         if (ret < 0)
  99                 return ret;
 100
 101         return 0;
 102 }
 103
 104 static int owl_serial_ofdata_to_platdata(struct udevice *dev)
 105 {
 106         struct owl_serial_priv *priv = dev_get_priv(dev);
 107
 108         priv->base = dev_read_addr(dev);
 109         if (priv->base == FDT_ADDR_T_NONE)
 110                 return -EINVAL;
 111
 112         return 0;
 113 }
 114
 115 static const struct dm_serial_ops owl_serial_ops = {
 116         .putc = owl_serial_putc,
 117         .pending = owl_serial_pending,
 118         .getc = owl_serial_getc,
 119         .setbrg = owl_serial_setbrg,
 120 };
 121
 122 static const struct udevice_id owl_serial_ids[] = {
 123         { .compatible = "actions,owl-uart" },
 124         { }
 125 };
 126
 127 U_BOOT_DRIVER(serial_owl) = {
 128         .name = "serial_owl",
 129         .id = UCLASS_SERIAL,
 130         .of_match = owl_serial_ids,
 131         .ofdata_to_platdata = owl_serial_ofdata_to_platdata,
 132         .priv_auto_alloc_size = sizeof(struct owl_serial_priv),
 133         .probe = owl_serial_probe,
 134         .ops = &owl_serial_ops,
 135 };