serial_owl.c
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// SPDX-License-Identifier: GPL-2.0+
/*
* Actions Semi OWL SoCs UART driver
*
* Copyright (C) 2015 Actions Semi Co., Ltd.
* Copyright (C) 2018 Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
*/
#include <common.h>
#include <clk.h>
#include <dm.h>
#include <errno.h>
#include <fdtdec.h>
#include <serial.h>
#include <asm/io.h>
#include <asm/types.h>
/* UART Registers */
#define OWL_UART_CTL (0x0000)
#define OWL_UART_RXDAT (0x0004)
#define OWL_UART_TXDAT (0x0008)
#define OWL_UART_STAT (0x000C)
/* UART_CTL Register Definitions */
#define OWL_UART_CTL_PRS_NONE GENMASK(6, 4)
#define OWL_UART_CTL_STPS BIT(2)
#define OWL_UART_CTL_DWLS 3
/* UART_STAT Register Definitions */
#define OWL_UART_STAT_TFES BIT(10) /* TX FIFO Empty Status */
#define OWL_UART_STAT_RFFS BIT(9) /* RX FIFO full Status */
#define OWL_UART_STAT_TFFU BIT(6) /* TX FIFO full Status */
#define OWL_UART_STAT_RFEM BIT(5) /* RX FIFO Empty Status */
struct owl_serial_priv {
phys_addr_t base;
};
int owl_serial_setbrg(struct udevice *dev, int baudrate)
{
/* Driver supports only fixed baudrate */
return 0;
}
static int owl_serial_getc(struct udevice *dev)
{
struct owl_serial_priv *priv = dev_get_priv(dev);
if (readl(priv->base + OWL_UART_STAT) & OWL_UART_STAT_RFEM)
return -EAGAIN;
return (int)(readl(priv->base + OWL_UART_RXDAT));
}
static int owl_serial_putc(struct udevice *dev, const char ch)
{
struct owl_serial_priv *priv = dev_get_priv(dev);
if (readl(priv->base + OWL_UART_STAT) & OWL_UART_STAT_TFFU)
return -EAGAIN;
writel(ch, priv->base + OWL_UART_TXDAT);
return 0;
}
static int owl_serial_pending(struct udevice *dev, bool input)
{
struct owl_serial_priv *priv = dev_get_priv(dev);
unsigned int stat = readl(priv->base + OWL_UART_STAT);
if (input)
return !(stat & OWL_UART_STAT_RFEM);
else
return !(stat & OWL_UART_STAT_TFES);
}
static int owl_serial_probe(struct udevice *dev)
{
struct owl_serial_priv *priv = dev_get_priv(dev);
struct clk clk;
u32 uart_ctl;
int ret;
/* Set data, parity and stop bits */
uart_ctl = readl(priv->base + OWL_UART_CTL);
uart_ctl &= ~(OWL_UART_CTL_PRS_NONE);
uart_ctl &= ~(OWL_UART_CTL_STPS);
uart_ctl |= OWL_UART_CTL_DWLS;
writel(uart_ctl, priv->base + OWL_UART_CTL);
/* Enable UART clock */
ret = clk_get_by_index(dev, 0, &clk);
if (ret < 0)
return ret;
ret = clk_enable(&clk);
if (ret < 0)
return ret;
return 0;
}
static int owl_serial_ofdata_to_platdata(struct udevice *dev)
{
struct owl_serial_priv *priv = dev_get_priv(dev);
priv->base = dev_read_addr(dev);
if (priv->base == FDT_ADDR_T_NONE)
return -EINVAL;
return 0;
}
static const struct dm_serial_ops owl_serial_ops = {
.putc = owl_serial_putc,
.pending = owl_serial_pending,
.getc = owl_serial_getc,
.setbrg = owl_serial_setbrg,
};
static const struct udevice_id owl_serial_ids[] = {
{ .compatible = "actions,s900-serial" },
{ }
};
U_BOOT_DRIVER(serial_owl) = {
.name = "serial_owl",
.id = UCLASS_SERIAL,
.of_match = owl_serial_ids,
.ofdata_to_platdata = owl_serial_ofdata_to_platdata,
.priv_auto_alloc_size = sizeof(struct owl_serial_priv),
.probe = owl_serial_probe,
.ops = &owl_serial_ops,
};