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Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of version 2 of the gnu general public license as published by the free software foundation extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 107 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Steve Winslow <swinslow@gmail.com> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190528171438.615055994@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
194 lines
5.6 KiB
C
194 lines
5.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Clock event driver for the CS5535/CS5536
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*
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* Copyright (C) 2006, Advanced Micro Devices, Inc.
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* Copyright (C) 2007 Andres Salomon <dilinger@debian.org>
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* Copyright (C) 2009 Andres Salomon <dilinger@collabora.co.uk>
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*
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* The MFGPTs are documented in AMD Geode CS5536 Companion Device Data Book.
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*/
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#include <linux/kernel.h>
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#include <linux/irq.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <linux/cs5535.h>
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#include <linux/clockchips.h>
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#define DRV_NAME "cs5535-clockevt"
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static int timer_irq;
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module_param_hw_named(irq, timer_irq, int, irq, 0644);
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MODULE_PARM_DESC(irq, "Which IRQ to use for the clock source MFGPT ticks.");
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/*
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* We are using the 32.768kHz input clock - it's the only one that has the
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* ranges we find desirable. The following table lists the suitable
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* divisors and the associated Hz, minimum interval and the maximum interval:
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*
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* Divisor Hz Min Delta (s) Max Delta (s)
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* 1 32768 .00048828125 2.000
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* 2 16384 .0009765625 4.000
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* 4 8192 .001953125 8.000
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* 8 4096 .00390625 16.000
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* 16 2048 .0078125 32.000
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* 32 1024 .015625 64.000
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* 64 512 .03125 128.000
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* 128 256 .0625 256.000
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* 256 128 .125 512.000
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*/
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static struct cs5535_mfgpt_timer *cs5535_event_clock;
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/* Selected from the table above */
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#define MFGPT_DIVISOR 16
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#define MFGPT_SCALE 4 /* divisor = 2^(scale) */
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#define MFGPT_HZ (32768 / MFGPT_DIVISOR)
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#define MFGPT_PERIODIC (MFGPT_HZ / HZ)
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/*
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* The MFGPT timers on the CS5536 provide us with suitable timers to use
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* as clock event sources - not as good as a HPET or APIC, but certainly
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* better than the PIT. This isn't a general purpose MFGPT driver, but
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* a simplified one designed specifically to act as a clock event source.
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* For full details about the MFGPT, please consult the CS5536 data sheet.
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*/
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static void disable_timer(struct cs5535_mfgpt_timer *timer)
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{
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/* avoid races by clearing CMP1 and CMP2 unconditionally */
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cs5535_mfgpt_write(timer, MFGPT_REG_SETUP,
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(uint16_t) ~MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP1 |
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MFGPT_SETUP_CMP2);
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}
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static void start_timer(struct cs5535_mfgpt_timer *timer, uint16_t delta)
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{
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cs5535_mfgpt_write(timer, MFGPT_REG_CMP2, delta);
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cs5535_mfgpt_write(timer, MFGPT_REG_COUNTER, 0);
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cs5535_mfgpt_write(timer, MFGPT_REG_SETUP,
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MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
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}
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static int mfgpt_shutdown(struct clock_event_device *evt)
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{
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disable_timer(cs5535_event_clock);
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return 0;
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}
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static int mfgpt_set_periodic(struct clock_event_device *evt)
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{
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disable_timer(cs5535_event_clock);
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start_timer(cs5535_event_clock, MFGPT_PERIODIC);
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return 0;
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}
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static int mfgpt_next_event(unsigned long delta, struct clock_event_device *evt)
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{
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start_timer(cs5535_event_clock, delta);
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return 0;
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}
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static struct clock_event_device cs5535_clockevent = {
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.name = DRV_NAME,
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.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
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.set_state_shutdown = mfgpt_shutdown,
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.set_state_periodic = mfgpt_set_periodic,
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.set_state_oneshot = mfgpt_shutdown,
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.tick_resume = mfgpt_shutdown,
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.set_next_event = mfgpt_next_event,
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.rating = 250,
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};
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static irqreturn_t mfgpt_tick(int irq, void *dev_id)
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{
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uint16_t val = cs5535_mfgpt_read(cs5535_event_clock, MFGPT_REG_SETUP);
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/* See if the interrupt was for us */
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if (!(val & (MFGPT_SETUP_SETUP | MFGPT_SETUP_CMP2 | MFGPT_SETUP_CMP1)))
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return IRQ_NONE;
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/* Turn off the clock (and clear the event) */
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disable_timer(cs5535_event_clock);
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if (clockevent_state_detached(&cs5535_clockevent) ||
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clockevent_state_shutdown(&cs5535_clockevent))
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return IRQ_HANDLED;
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/* Clear the counter */
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cs5535_mfgpt_write(cs5535_event_clock, MFGPT_REG_COUNTER, 0);
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/* Restart the clock in periodic mode */
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if (clockevent_state_periodic(&cs5535_clockevent))
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cs5535_mfgpt_write(cs5535_event_clock, MFGPT_REG_SETUP,
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MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
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cs5535_clockevent.event_handler(&cs5535_clockevent);
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return IRQ_HANDLED;
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}
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static struct irqaction mfgptirq = {
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.handler = mfgpt_tick,
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.flags = IRQF_NOBALANCING | IRQF_TIMER | IRQF_SHARED,
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.name = DRV_NAME,
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};
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static int __init cs5535_mfgpt_init(void)
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{
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struct cs5535_mfgpt_timer *timer;
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int ret;
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uint16_t val;
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timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
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if (!timer) {
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printk(KERN_ERR DRV_NAME ": Could not allocate MFGPT timer\n");
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return -ENODEV;
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}
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cs5535_event_clock = timer;
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/* Set up the IRQ on the MFGPT side */
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if (cs5535_mfgpt_setup_irq(timer, MFGPT_CMP2, &timer_irq)) {
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printk(KERN_ERR DRV_NAME ": Could not set up IRQ %d\n",
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timer_irq);
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goto err_timer;
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}
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/* And register it with the kernel */
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ret = setup_irq(timer_irq, &mfgptirq);
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if (ret) {
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printk(KERN_ERR DRV_NAME ": Unable to set up the interrupt.\n");
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goto err_irq;
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}
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/* Set the clock scale and enable the event mode for CMP2 */
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val = MFGPT_SCALE | (3 << 8);
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cs5535_mfgpt_write(cs5535_event_clock, MFGPT_REG_SETUP, val);
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/* Set up the clock event */
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printk(KERN_INFO DRV_NAME
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": Registering MFGPT timer as a clock event, using IRQ %d\n",
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timer_irq);
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clockevents_config_and_register(&cs5535_clockevent, MFGPT_HZ,
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0xF, 0xFFFE);
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return 0;
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err_irq:
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cs5535_mfgpt_release_irq(cs5535_event_clock, MFGPT_CMP2, &timer_irq);
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err_timer:
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cs5535_mfgpt_free_timer(cs5535_event_clock);
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printk(KERN_ERR DRV_NAME ": Unable to set up the MFGPT clock source\n");
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return -EIO;
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}
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module_init(cs5535_mfgpt_init);
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MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
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MODULE_DESCRIPTION("CS5535/CS5536 MFGPT clock event driver");
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MODULE_LICENSE("GPL");
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