Commit 3917c269 authored by Stephen Warren's avatar Stephen Warren Committed by Tom Rini
Browse files

serial: add BCM283x mini UART driver



The RPi3 typically uses the regular UART for high-speed communication with
the Bluetooth device, leaving us the mini UART to use for the serial
console. Add support for this UART so we can use it.
Signed-off-by: Stephen Warren's avatarStephen Warren <swarren@wwwdotorg.org>
parent 92667e89
......@@ -38,6 +38,7 @@ obj-$(CONFIG_UNIPHIER_SERIAL) += serial_uniphier.o
obj-$(CONFIG_STM32_SERIAL) += serial_stm32.o
obj-$(CONFIG_PIC32_SERIAL) += serial_pic32.o
obj-$(CONFIG_STM32X7_SERIAL) += serial_stm32x7.o
obj-$(CONFIG_BCM283X_MU_SERIAL) += serial_bcm283x_mu.o
ifndef CONFIG_SPL_BUILD
obj-$(CONFIG_USB_TTY) += usbtty.o
......
/*
* (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>
*
* SPDX-License-Identifier: GPL-2.0+
*/
/* Simple U-Boot driver for the BCM283x mini UART */
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <watchdog.h>
#include <asm/io.h>
#include <serial.h>
#include <dm/platform_data/serial_bcm283x_mu.h>
#include <linux/compiler.h>
#include <fdtdec.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_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)
return 0;
divider = plat->clock / (baudrate * 8);
writel(BCM283X_MU_LCR_DATA_SIZE_8, &regs->lcr);
writel(divider - 1, &regs->baud);
return 0;
}
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);
priv->regs = (struct bcm283x_mu_regs *)plat->base;
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(&regs->lsr) & BCM283X_MU_LSR_RX_READY))
return -EAGAIN;
data = readl(&regs->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(&regs->lsr) & BCM283X_MU_LSR_TX_EMPTY))
return -EAGAIN;
/* Send the character */
writel(data, &regs->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 = readl(&regs->lsr);
if (input) {
WATCHDOG_RESET();
return lsr & BCM283X_MU_LSR_RX_READY;
} else {
return !(lsr & BCM283X_MU_LSR_TX_IDLE);
}
}
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,
};
U_BOOT_DRIVER(serial_bcm283x_mu) = {
.name = "serial_bcm283x_mu",
.id = UCLASS_SERIAL,
.platdata_auto_alloc_size = sizeof(struct bcm283x_mu_serial_platdata),
.probe = bcm283x_mu_serial_probe,
.ops = &bcm283x_mu_serial_ops,
.flags = DM_FLAG_PRE_RELOC,
.priv_auto_alloc_size = sizeof(struct bcm283x_mu_priv),
};
/*
* (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org>
*
* Derived from pl01x code:
* Copyright (c) 2014 Google, Inc
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef __serial_bcm283x_mu_h
#define __serial_bcm283x_mu_h
/*
*Information about a serial port
*
* @base: Register base address
*/
struct bcm283x_mu_serial_platdata {
unsigned long base;
unsigned int clock;
bool skip_init;
};
#endif
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