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/*
* (c) 2015 Paul Thacker <paul.thacker@microchip.com>
*
* SPDX-License-Identifier: GPL-2.0+
*
*/
#include <common.h>
#include <clk.h>
#include <dm.h>
#include <serial.h>
#include <wait_bit.h>
#include <mach/pic32.h>
#include <dt-bindings/clock/microchip,clock.h>
DECLARE_GLOBAL_DATA_PTR;
/* UART Control Registers */
#define U_MOD 0x00
#define U_MODCLR (U_MOD + _CLR_OFFSET)
#define U_MODSET (U_MOD + _SET_OFFSET)
#define U_STA 0x10
#define U_STACLR (U_STA + _CLR_OFFSET)
#define U_STASET (U_STA + _SET_OFFSET)
#define U_TXR 0x20
#define U_RXR 0x30
#define U_BRG 0x40
/* U_MOD bits */
#define UART_ENABLE BIT(15)
/* U_STA bits */
#define UART_RX_ENABLE BIT(12)
#define UART_TX_BRK BIT(11)
#define UART_TX_ENABLE BIT(10)
#define UART_TX_FULL BIT(9)
#define UART_TX_EMPTY BIT(8)
#define UART_RX_OVER BIT(1)
#define UART_RX_DATA_AVAIL BIT(0)
struct pic32_uart_priv {
void __iomem *base;
ulong uartclk;
};
/*
* Initialize the serial port with the given baudrate.
* The settings are always 8 data bits, no parity, 1 stop bit, no start bits.
*/
static int pic32_serial_init(void __iomem *base, ulong clk, u32 baudrate)
{
u32 div = DIV_ROUND_CLOSEST(clk, baudrate * 16);
/* wait for TX FIFO to empty */
wait_for_bit(__func__, base + U_STA, UART_TX_EMPTY,
true, CONFIG_SYS_HZ, false);
/* send break */
writel(UART_TX_BRK, base + U_STASET);
/* disable and clear mode */
writel(0, base + U_MOD);
writel(0, base + U_STA);
/* set baud rate generator */
writel(div - 1, base + U_BRG);
/* enable the UART for TX and RX */
writel(UART_TX_ENABLE | UART_RX_ENABLE, base + U_STASET);
/* enable the UART */
writel(UART_ENABLE, base + U_MODSET);
return 0;
}
/* Check whether any char pending in RX fifo */
static int pic32_uart_pending_input(void __iomem *base)
{
/* check if rx buffer overrun error has occurred */
if (readl(base + U_STA) & UART_RX_OVER) {
readl(base + U_RXR);
/* clear overrun error to keep receiving */
writel(UART_RX_OVER, base + U_STACLR);
}
/* In PIC32 there is no way to know number of outstanding
* chars in rx-fifo. Only it can be known whether there is any.
*/
return readl(base + U_STA) & UART_RX_DATA_AVAIL;
}
static int pic32_uart_pending(struct udevice *dev, bool input)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
if (input)
return pic32_uart_pending_input(priv->base);
return !(readl(priv->base + U_STA) & UART_TX_EMPTY);
}
static int pic32_uart_setbrg(struct udevice *dev, int baudrate)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
return pic32_serial_init(priv->base, priv->uartclk, baudrate);
}
static int pic32_uart_putc(struct udevice *dev, const char ch)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
/* Check if Tx FIFO is full */
if (readl(priv->base + U_STA) & UART_TX_FULL)
return -EAGAIN;
/* pump the char to tx buffer */
writel(ch, priv->base + U_TXR);
return 0;
}
static int pic32_uart_getc(struct udevice *dev)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
/* return error if RX fifo is empty */
if (!pic32_uart_pending_input(priv->base))
return -EAGAIN;
/* read the character from rx buffer */
return readl(priv->base + U_RXR) & 0xff;
}
static int pic32_uart_probe(struct udevice *dev)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
struct udevice *clkdev;
fdt_addr_t addr;
fdt_size_t size;
int ret;
/* get address */
addr = fdtdec_get_addr_size(gd->fdt_blob, dev->of_offset, "reg", &size);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
priv->base = ioremap(addr, size);
/* get clock rate */
ret = clk_get_by_index(dev, 0, &clkdev);
if (ret < 0)
return ret;
priv->uartclk = clk_get_periph_rate(clkdev, ret);
/* initialize serial */
return pic32_serial_init(priv->base, priv->uartclk, CONFIG_BAUDRATE);
}
static const struct dm_serial_ops pic32_uart_ops = {
.putc = pic32_uart_putc,
.pending = pic32_uart_pending,
.getc = pic32_uart_getc,
.setbrg = pic32_uart_setbrg,
};
static const struct udevice_id pic32_uart_ids[] = {
{ .compatible = "microchip,pic32mzda-uart" },
{}
};
U_BOOT_DRIVER(pic32_serial) = {
.name = "pic32-uart",
.id = UCLASS_SERIAL,
.of_match = pic32_uart_ids,
.probe = pic32_uart_probe,
.ops = &pic32_uart_ops,
.flags = DM_FLAG_PRE_RELOC,
.priv_auto_alloc_size = sizeof(struct pic32_uart_priv),
};
#ifdef CONFIG_DEBUG_UART_PIC32
#include <debug_uart.h>
static inline void _debug_uart_init(void)
{
void __iomem *base = (void __iomem *)CONFIG_DEBUG_UART_BASE;
pic32_serial_init(base, CONFIG_DEBUG_UART_CLOCK, CONFIG_BAUDRATE);
}
static inline void _debug_uart_putc(int ch)
{
writel(ch, CONFIG_DEBUG_UART_BASE + U_TXR);
}
DEBUG_UART_FUNCS
#endif
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