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 #include <linux/bitops.h>
  18
  19 /* UART Registers */
  20 #define OWL_UART_CTL                    (0x0000)
  21 #define OWL_UART_RXDAT                  (0x0004)
  22 #define OWL_UART_TXDAT                  (0x0008)
  23 #define OWL_UART_STAT                   (0x000C)
  24
  25 /* UART_CTL Register Definitions */
  26 #define OWL_UART_CTL_PRS_NONE           GENMASK(6, 4)
  27 #define OWL_UART_CTL_STPS               BIT(2)
  28 #define OWL_UART_CTL_DWLS               3
  29
  30 /* UART_STAT Register Definitions */
  31 #define OWL_UART_STAT_TFES              BIT(10) /* TX FIFO Empty Status */
  32 #define OWL_UART_STAT_RFFS              BIT(9)  /* RX FIFO full Status */
  33 #define OWL_UART_STAT_TFFU              BIT(6)  /* TX FIFO full Status */
  34 #define OWL_UART_STAT_RFEM              BIT(5)  /* RX FIFO Empty Status */
  35
  36 struct owl_serial_priv {
  37         phys_addr_t base;
  38 };
  39
  40 int owl_serial_setbrg(struct udevice *dev, int baudrate)
  41 {
  42         /* Driver supports only fixed baudrate */
  43         return 0;
  44 }
  45
  46 static int owl_serial_getc(struct udevice *dev)
  47 {
  48         struct owl_serial_priv *priv = dev_get_priv(dev);
  49
  50         if (readl(priv->base + OWL_UART_STAT) & OWL_UART_STAT_RFEM)
  51                 return -EAGAIN;
  52
  53         return (int)(readl(priv->base + OWL_UART_RXDAT));
  54 }
  55
  56 static int owl_serial_putc(struct udevice *dev, const char ch)
  57 {
  58         struct owl_serial_priv *priv = dev_get_priv(dev);
  59
  60         if (readl(priv->base + OWL_UART_STAT) & OWL_UART_STAT_TFFU)
  61                 return -EAGAIN;
  62
  63         writel(ch, priv->base + OWL_UART_TXDAT);
  64
  65         return 0;
  66 }
  67
  68 static int owl_serial_pending(struct udevice *dev, bool input)
  69 {
  70         struct owl_serial_priv *priv = dev_get_priv(dev);
  71         unsigned int stat = readl(priv->base + OWL_UART_STAT);
  72
  73         if (input)
  74                 return !(stat & OWL_UART_STAT_RFEM);
  75         else
  76                 return !(stat & OWL_UART_STAT_TFES);
  77 }
  78
  79 static int owl_serial_probe(struct udevice *dev)
  80 {
  81         struct owl_serial_priv *priv = dev_get_priv(dev);
  82         struct clk clk;
  83         u32 uart_ctl;
  84         int ret;
  85
  86         /* Set data, parity and stop bits */
  87         uart_ctl = readl(priv->base + OWL_UART_CTL);
  88         uart_ctl &= ~(OWL_UART_CTL_PRS_NONE);
  89         uart_ctl &= ~(OWL_UART_CTL_STPS);
  90         uart_ctl |= OWL_UART_CTL_DWLS;
  91         writel(uart_ctl, priv->base + OWL_UART_CTL);
  92
  93         /* Enable UART clock */
  94         ret = clk_get_by_index(dev, 0, &clk);
  95         if (ret < 0)
  96                 return ret;
  97
  98         ret = clk_enable(&clk);
  99         if (ret < 0)
 100                 return ret;
 101
 102         return 0;
 103 }
 104
 105 static int owl_serial_ofdata_to_platdata(struct udevice *dev)
 106 {
 107         struct owl_serial_priv *priv = dev_get_priv(dev);
 108
 109         priv->base = dev_read_addr(dev);
 110         if (priv->base == FDT_ADDR_T_NONE)
 111                 return -EINVAL;
 112
 113         return 0;
 114 }
 115
 116 static const struct dm_serial_ops owl_serial_ops = {
 117         .putc = owl_serial_putc,
 118         .pending = owl_serial_pending,
 119         .getc = owl_serial_getc,
 120         .setbrg = owl_serial_setbrg,
 121 };
 122
 123 static const struct udevice_id owl_serial_ids[] = {
 124         { .compatible = "actions,owl-uart" },
 125         { }
 126 };
 127
 128 U_BOOT_DRIVER(serial_owl) = {
 129         .name = "serial_owl",
 130         .id = UCLASS_SERIAL,
 131         .of_match = owl_serial_ids,
 132         .ofdata_to_platdata = owl_serial_ofdata_to_platdata,
 133         .priv_auto_alloc_size = sizeof(struct owl_serial_priv),
 134         .probe = owl_serial_probe,
 135         .ops = &owl_serial_ops,
 136 };