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Release 4.13 drivers/tty/serial/owl-uart.c

/*
 * Actions Semi Owl family serial console
 *
 * Copyright 2013 Actions Semi Inc.
 * Author: Actions Semi, Inc.
 *
 * Copyright (c) 2016-2017 Andreas Färber
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/console.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/serial.h>
#include <linux/serial_core.h>


#define OWL_UART_CTL	0x000

#define OWL_UART_TXDAT	0x008

#define OWL_UART_STAT	0x00c


#define OWL_UART_CTL_TRFS_TX		BIT(14)

#define OWL_UART_CTL_EN			BIT(15)

#define OWL_UART_CTL_RXIE		BIT(18)

#define OWL_UART_CTL_TXIE		BIT(19)


#define OWL_UART_STAT_RIP		BIT(0)

#define OWL_UART_STAT_TIP		BIT(1)

#define OWL_UART_STAT_TFFU		BIT(6)

#define OWL_UART_STAT_TRFL_MASK		(0x1f << 11)

#define OWL_UART_STAT_UTBB		BIT(17)


static inline void owl_uart_write(struct uart_port *port, u32 val, unsigned int off) { writel(val, port->membase + off); }

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static inline u32 owl_uart_read(struct uart_port *port, unsigned int off) { return readl(port->membase + off); }

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#ifdef CONFIG_SERIAL_OWL_CONSOLE
static void owl_console_putchar(struct uart_port *port, int ch) { if (!port->membase) return; while (owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU) cpu_relax(); owl_uart_write(port, ch, OWL_UART_TXDAT); }

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static void owl_uart_port_write(struct uart_port *port, const char *s, u_int count) { u32 old_ctl, val; unsigned long flags; int locked; local_irq_save(flags); if (port->sysrq) locked = 0; else if (oops_in_progress) locked = spin_trylock(&port->lock); else { spin_lock(&port->lock); locked = 1; } old_ctl = owl_uart_read(port, OWL_UART_CTL); val = old_ctl | OWL_UART_CTL_TRFS_TX; /* disable IRQ */ val &= ~(OWL_UART_CTL_RXIE | OWL_UART_CTL_TXIE); owl_uart_write(port, val, OWL_UART_CTL); uart_console_write(port, s, count, owl_console_putchar); /* wait until all contents have been sent out */ while (owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TRFL_MASK) cpu_relax(); /* clear IRQ pending */ val = owl_uart_read(port, OWL_UART_STAT); val |= OWL_UART_STAT_TIP | OWL_UART_STAT_RIP; owl_uart_write(port, val, OWL_UART_STAT); owl_uart_write(port, old_ctl, OWL_UART_CTL); if (locked) spin_unlock(&port->lock); local_irq_restore(flags); }

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static void owl_uart_early_console_write(struct console *co, const char *s, u_int count) { struct earlycon_device *dev = co->data; owl_uart_port_write(&dev->port, s, count); }

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static int __init owl_uart_early_console_setup(struct earlycon_device *device, const char *opt) { if (!device->port.membase) return -ENODEV; device->con->write = owl_uart_early_console_write; return 0; }

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OF_EARLYCON_DECLARE(owl, "actions,owl-uart", owl_uart_early_console_setup); #endif /* CONFIG_SERIAL_OWL_CONSOLE */

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