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02239f0a42
Add core functions to handle writes to the ep93xx software locked registers. There are a number of registers in the EP93xx System Controller that require a write to the software lock register before they can be updated. This patch adds a number of exported functions to the ep93xx core that handle this access. The software locked clock divider registers, VidClkDiv, MIRClkDiv, I2SClkDiv and KeyTchClkDiv would typically involve writing a specific value to the register. To support this the ep93xx_syscon_swlocked_write() function is provided. For the DeviceCfg register it's more typical to only need to set or clear a single bit. A generic ep93xx_devcfg_set_clear() function is provided to handle both operations. Two inline functions, ep93xx_devcfg_set_bits() and ep93xx_devcfg_clear_bits() are also provided to improve code readability. In addition, the remaining bits in the System Controller Device Config Register have been documented and the previously defined names shortened. All code paths that use this functionality have been updated except for arch/arm/kernel/crunch.c. That code is in a context switch path, which is not reentrant, so it is safe against itself. Cc: Lennert Buytenhek <buytenh@wantstofly.org> Cc: Matthias Kaehlcke <matthias@kaehlcke.net> Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Acked-by: Ryan Mallon <ryan@bluewatersys.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
89 lines
2.1 KiB
C
89 lines
2.1 KiB
C
/*
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* arch/arm/kernel/crunch.c
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* Cirrus MaverickCrunch context switching and handling
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*
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* Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <mach/ep93xx-regs.h>
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#include <asm/thread_notify.h>
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struct crunch_state *crunch_owner;
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void crunch_task_release(struct thread_info *thread)
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{
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local_irq_disable();
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if (crunch_owner == &thread->crunchstate)
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crunch_owner = NULL;
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local_irq_enable();
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}
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static int crunch_enabled(u32 devcfg)
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{
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return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA);
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}
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static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
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{
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struct thread_info *thread = (struct thread_info *)t;
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struct crunch_state *crunch_state;
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u32 devcfg;
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crunch_state = &thread->crunchstate;
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switch (cmd) {
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case THREAD_NOTIFY_FLUSH:
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memset(crunch_state, 0, sizeof(*crunch_state));
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/*
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* FALLTHROUGH: Ensure we don't try to overwrite our newly
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* initialised state information on the first fault.
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*/
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case THREAD_NOTIFY_RELEASE:
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crunch_task_release(thread);
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break;
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case THREAD_NOTIFY_SWITCH:
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devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG);
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if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
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/*
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* We don't use ep93xx_syscon_swlocked_write() here
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* because we are on the context switch path and
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* preemption is already disabled.
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*/
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devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA;
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__raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
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__raw_writel(devcfg, EP93XX_SYSCON_DEVCFG);
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}
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break;
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block crunch_notifier_block = {
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.notifier_call = crunch_do,
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};
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static int __init crunch_init(void)
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{
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thread_register_notifier(&crunch_notifier_block);
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elf_hwcap |= HWCAP_CRUNCH;
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return 0;
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}
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late_initcall(crunch_init);
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