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// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org>
*
* Derived from pl01x code:
*
* (C) Copyright 2000
* Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
*
* (C) Copyright 2004
* ARM Ltd.
* Philippe Robin, <philippe.robin@arm.com>
*/
/* Simple U-Boot driver for the BCM283x mini UART */
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <watchdog.h>
#include <asm/gpio.h>
#include <asm/io.h>
#include <serial.h>
#include <dm/platform_data/serial_bcm283x_mu.h>
#include <dm/pinctrl.h>
#include <linux/bitops.h>
#include <linux/compiler.h>
struct bcm283x_mu_regs {
u32 io;
u32 iir;
u32 ier;
u32 lcr;
u32 mcr;
u32 lsr;
u32 msr;
u32 scratch;
u32 cntl;
u32 stat;
u32 baud;
};
#define BCM283X_MU_LCR_DATA_SIZE_8 3
#define BCM283X_MU_LSR_TX_IDLE BIT(6)
/* This actually means not full, but is named not empty in the docs */
#define BCM283X_MU_LSR_TX_EMPTY BIT(5)
#define BCM283X_MU_LSR_RX_READY BIT(0)
struct bcm283x_mu_priv {
struct bcm283x_mu_regs *regs;
};
static int bcm283x_mu_serial_getc(struct udevice *dev);
static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
{
struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
struct bcm283x_mu_priv *priv = dev_get_priv(dev);
struct bcm283x_mu_regs *regs = priv->regs;
u32 divider;
if (plat->skip_init)
goto out;
divider = plat->clock / (baudrate * 8);
writel(BCM283X_MU_LCR_DATA_SIZE_8, ®s->lcr);
writel(divider - 1, ®s->baud);
out:
/* Flush the RX queue - all data in there is bogus */
while (bcm283x_mu_serial_getc(dev) != -EAGAIN) ;
return 0;
}
static int bcm283x_mu_serial_getc(struct udevice *dev)
{
struct bcm283x_mu_priv *priv = dev_get_priv(dev);
struct bcm283x_mu_regs *regs = priv->regs;
u32 data;
/* Wait until there is data in the FIFO */
if (!(readl(®s->lsr) & BCM283X_MU_LSR_RX_READY))
return -EAGAIN;
data = readl(®s->io);
return (int)data;
}
static int bcm283x_mu_serial_putc(struct udevice *dev, const char data)
{
struct bcm283x_mu_priv *priv = dev_get_priv(dev);
struct bcm283x_mu_regs *regs = priv->regs;
/* Wait until there is space in the FIFO */
if (!(readl(®s->lsr) & BCM283X_MU_LSR_TX_EMPTY))
return -EAGAIN;
/* Send the character */
writel(data, ®s->io);
return 0;
}
static int bcm283x_mu_serial_pending(struct udevice *dev, bool input)
{
struct bcm283x_mu_priv *priv = dev_get_priv(dev);
struct bcm283x_mu_regs *regs = priv->regs;
unsigned int lsr;
lsr = readl(®s->lsr);
if (input) {
WATCHDOG_RESET();
return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0;
} else {
return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1;
}
}
static const struct dm_serial_ops bcm283x_mu_serial_ops = {
.putc = bcm283x_mu_serial_putc,
.pending = bcm283x_mu_serial_pending,
.getc = bcm283x_mu_serial_getc,
.setbrg = bcm283x_mu_serial_setbrg,
};
#if CONFIG_IS_ENABLED(OF_CONTROL)
static const struct udevice_id bcm283x_mu_serial_id[] = {
{.compatible = "brcm,bcm2835-aux-uart"},
{}
};
/*
* Check if this serial device is muxed
*
* The serial device will only work properly if it has been muxed to the serial
* pins by firmware. Check whether that happened here.
*
* @return true if serial device is muxed, false if not
*/
static bool bcm283x_is_serial_muxed(void)
{
int serial_gpio = 15;
struct udevice *dev;
if (uclass_first_device(UCLASS_PINCTRL, &dev) || !dev)
return false;
if (pinctrl_get_gpio_mux(dev, 0, serial_gpio) != BCM2835_GPIO_ALT5)
return false;
return true;
}
static int bcm283x_mu_serial_probe(struct udevice *dev)
{
struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
struct bcm283x_mu_priv *priv = dev_get_priv(dev);
fdt_addr_t addr;
/* Don't spawn the device if it's not muxed */
if (!bcm283x_is_serial_muxed())
return -ENODEV;
/*
* Read the ofdata here rather than in an ofdata_to_platdata() method
* since we need the soc simple-bus to be probed so that the 'ranges'
* property is used.
*/
addr = dev_read_addr(dev);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
plat->base = addr;
plat->clock = dev_read_u32_default(dev, "clock", 1);
/*
* TODO: Reinitialization doesn't always work for now, just skip
* init always - we know we're already initialized
*/
plat->skip_init = true;
priv->regs = (struct bcm283x_mu_regs *)plat->base;
return 0;
}
#endif
U_BOOT_DRIVER(serial_bcm283x_mu) = {
.name = "serial_bcm283x_mu",
.id = UCLASS_SERIAL,
.of_match = of_match_ptr(bcm283x_mu_serial_id),
.plat_auto = sizeof(struct bcm283x_mu_serial_platdata),
.probe = bcm283x_mu_serial_probe,
.ops = &bcm283x_mu_serial_ops,
#if !CONFIG_IS_ENABLED(OF_CONTROL) || CONFIG_IS_ENABLED(OF_BOARD)
.flags = DM_FLAG_PRE_RELOC,
#endif
.priv_auto = sizeof(struct bcm283x_mu_priv),
};
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