sead3-pic32-bus.c
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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
*/
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/errno.h>
#define PIC32_NULL 0x00
#define PIC32_RD 0x01
#define PIC32_SYSRD 0x02
#define PIC32_WR 0x10
#define PIC32_SYSWR 0x20
#define PIC32_IRQ_CLR 0x40
#define PIC32_STATUS 0x80
#define DELAY() udelay(100) /* FIXME: needed? */
/* spinlock to ensure atomic access to PIC32 */
static DEFINE_SPINLOCK(pic32_bus_lock);
/* FIXME: io_remap these */
static void __iomem *bus_xfer = (void __iomem *)0xbf000600;
static void __iomem *bus_status = (void __iomem *)0xbf000060;
static inline unsigned int ioready(void)
{
return readl(bus_status) & 1;
}
static inline void wait_ioready(void)
{
do { } while (!ioready());
}
static inline void wait_ioclear(void)
{
do { } while (ioready());
}
static inline void check_ioclear(void)
{
if (ioready()) {
pr_debug("ioclear: initially busy\n");
do {
(void) readl(bus_xfer);
DELAY();
} while (ioready());
pr_debug("ioclear: cleared busy\n");
}
}
u32 pic32_bus_readl(u32 reg)
{
unsigned long flags;
u32 status, val;
spin_lock_irqsave(&pic32_bus_lock, flags);
check_ioclear();
writel((PIC32_RD << 24) | (reg & 0x00ffffff), bus_xfer);
DELAY();
wait_ioready();
status = readl(bus_xfer);
DELAY();
val = readl(bus_xfer);
wait_ioclear();
pr_debug("pic32_bus_readl: *%x -> %x (status=%x)\n", reg, val, status);
spin_unlock_irqrestore(&pic32_bus_lock, flags);
return val;
}
void pic32_bus_writel(u32 val, u32 reg)
{
unsigned long flags;
u32 status;
spin_lock_irqsave(&pic32_bus_lock, flags);
check_ioclear();
writel((PIC32_WR << 24) | (reg & 0x00ffffff), bus_xfer);
DELAY();
writel(val, bus_xfer);
DELAY();
wait_ioready();
status = readl(bus_xfer);
wait_ioclear();
pr_debug("pic32_bus_writel: *%x <- %x (status=%x)\n", reg, val, status);
spin_unlock_irqrestore(&pic32_bus_lock, flags);
}