LXR uboot/drivers/serial/serial

   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
  36struct owl_serial_priv {
  37        phys_addr_t base;
  38};
  39
  40int owl_serial_setbrg(struct udevice *dev, int baudrate)
  41{
  42        /* Driver supports only fixed baudrate */
  43        return 0;
  44}
  45
  46static 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
  56static 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
  68static 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
  79static 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
 105static int owl_serial_of_to_plat(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
 116static 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
 123static const struct udevice_id owl_serial_ids[] = {
 124        { .compatible = "actions,owl-uart" },
 125        { }
 126};
 127
 128U_BOOT_DRIVER(serial_owl) = {
 129        .name = "serial_owl",
 130        .id = UCLASS_SERIAL,
 131        .of_match = owl_serial_ids,
 132        .of_to_plat = owl_serial_of_to_plat,
 133        .priv_auto      =       sizeof(struct owl_serial_priv),
 134        .probe = owl_serial_probe,
 135        .ops = &owl_serial_ops,
 136};
 137