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/*
* This file contains driver for the Cadence Triple Timer Counter Rev 06
*
* Copyright (C) 2011-2013 Xilinx
*
* based on arch/mips/kernel/time.c timer driver
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* 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.
*/
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/slab.h>
#include <linux/sched_clock.h>
/*
* This driver configures the 2 16/32-bit count-up timers as follows:
*
* T1: Timer 1, clocksource for generic timekeeping
* T2: Timer 2, clockevent source for hrtimers
* T3: Timer 3, <unused>
*
* The input frequency to the timer module for emulation is 2.5MHz which is
* common to all the timer channels (T1, T2, and T3). With a pre-scaler of 32,
* the timers are clocked at 78.125KHz (12.8 us resolution).
* The input frequency to the timer module in silicon is configurable and
* obtained from device tree. The pre-scaler of 32 is used.
*/
/*
* Timer Register Offset Definitions of Timer 1, Increment base address by 4
* and use same offsets for Timer 2
*/
#define TTC_CLK_CNTRL_OFFSET 0x00 /* Clock Control Reg, RW */
#define TTC_CNT_CNTRL_OFFSET 0x0C /* Counter Control Reg, RW */
#define TTC_COUNT_VAL_OFFSET 0x18 /* Counter Value Reg, RO */
#define TTC_INTR_VAL_OFFSET 0x24 /* Interval Count Reg, RW */
#define TTC_ISR_OFFSET 0x54 /* Interrupt Status Reg, RO */
#define TTC_IER_OFFSET 0x60 /* Interrupt Enable Reg, RW */
#define TTC_CNT_CNTRL_DISABLE_MASK 0x1
#define TTC_CLK_CNTRL_CSRC_MASK (1 << 5) /* clock source */
#define TTC_CLK_CNTRL_PSV_MASK 0x1e
#define TTC_CLK_CNTRL_PSV_SHIFT 1
/*
* Setup the timers to use pre-scaling, using a fixed value for now that will
* work across most input frequency, but it may need to be more dynamic
*/
#define PRESCALE_EXPONENT 11 /* 2 ^ PRESCALE_EXPONENT = PRESCALE */
#define PRESCALE 2048 /* The exponent must match this */
#define CLK_CNTRL_PRESCALE ((PRESCALE_EXPONENT - 1) << 1)
#define CLK_CNTRL_PRESCALE_EN 1
#define CNT_CNTRL_RESET (1 << 4)
#define MAX_F_ERR 50
/**
* struct ttc_timer - This definition defines local timer structure
*
* @base_addr: Base address of timer
* @freq: Timer input clock frequency
* @clk: Associated clock source
* @clk_rate_change_nb Notifier block for clock rate changes
*/
struct ttc_timer {
void __iomem *base_addr;
unsigned long freq;
struct clk *clk;
struct notifier_block clk_rate_change_nb;
};
#define to_ttc_timer(x) \
container_of(x, struct ttc_timer, clk_rate_change_nb)
struct ttc_timer_clocksource {
u32 scale_clk_ctrl_reg_old;
u32 scale_clk_ctrl_reg_new;
struct ttc_timer ttc;
struct clocksource cs;
};
#define to_ttc_timer_clksrc(x) \
container_of(x, struct ttc_timer_clocksource, cs)
struct ttc_timer_clockevent {
struct ttc_timer ttc;
struct clock_event_device ce;
};
#define to_ttc_timer_clkevent(x) \
container_of(x, struct ttc_timer_clockevent, ce)
static void __iomem *ttc_sched_clock_val_reg;
/**
* ttc_set_interval - Set the timer interval value
*
* @timer: Pointer to the timer instance
* @cycles: Timer interval ticks
**/
static void ttc_set_interval(struct ttc_timer *timer,
unsigned long cycles)
{
u32 ctrl_reg;
/* Disable the counter, set the counter value and re-enable counter */
ctrl_reg = readl_relaxed(timer->base_addr + TTC_CNT_CNTRL_OFFSET);
ctrl_reg |= TTC_CNT_CNTRL_DISABLE_MASK;
writel_relaxed(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET);
writel_relaxed(cycles, timer->base_addr + TTC_INTR_VAL_OFFSET);
/*
* Reset the counter (0x10) so that it starts from 0, one-shot
* mode makes this needed for timing to be right.
*/
ctrl_reg |= CNT_CNTRL_RESET;
ctrl_reg &= ~TTC_CNT_CNTRL_DISABLE_MASK;
writel_relaxed(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET);
}
/**
* ttc_clock_event_interrupt - Clock event timer interrupt handler
*
* @irq: IRQ number of the Timer
* @dev_id: void pointer to the ttc_timer instance
*
* returns: Always IRQ_HANDLED - success
**/
static irqreturn_t ttc_clock_event_interrupt(int irq, void *dev_id)
{
struct ttc_timer_clockevent *ttce = dev_id;
struct ttc_timer *timer = &ttce->ttc;
/* Acknowledge the interrupt and call event handler */
readl_relaxed(timer->base_addr + TTC_ISR_OFFSET);
ttce->ce.event_handler(&ttce->ce);
return IRQ_HANDLED;
}
/**
* __ttc_clocksource_read - Reads the timer counter register
*
* returns: Current timer counter register value
**/
static cycle_t __ttc_clocksource_read(struct clocksource *cs)
{
struct ttc_timer *timer = &to_ttc_timer_clksrc(cs)->ttc;
return (cycle_t)readl_relaxed(timer->base_addr +
TTC_COUNT_VAL_OFFSET);
}
static u64 notrace ttc_sched_clock_read(void)
{
return readl_relaxed(ttc_sched_clock_val_reg);
}
/**
* ttc_set_next_event - Sets the time interval for next event
*
* @cycles: Timer interval ticks
* @evt: Address of clock event instance
*
* returns: Always 0 - success
**/
static int ttc_set_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt);
struct ttc_timer *timer = &ttce->ttc;
ttc_set_interval(timer, cycles);
return 0;
}
/**
* ttc_set_{shutdown|oneshot|periodic} - Sets the state of timer
*
* @evt: Address of clock event instance
**/
static int ttc_shutdown(struct clock_event_device *evt)
{
struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt);
struct ttc_timer *timer = &ttce->ttc;
u32 ctrl_reg;
ctrl_reg = readl_relaxed(timer->base_addr + TTC_CNT_CNTRL_OFFSET);
ctrl_reg |= TTC_CNT_CNTRL_DISABLE_MASK;
writel_relaxed(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET);
return 0;
}
static int ttc_set_periodic(struct clock_event_device *evt)
{
struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt);
struct ttc_timer *timer = &ttce->ttc;
ttc_set_interval(timer,
DIV_ROUND_CLOSEST(ttce->ttc.freq, PRESCALE * HZ));
return 0;
}
static int ttc_resume(struct clock_event_device *evt)
{
struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt);
struct ttc_timer *timer = &ttce->ttc;
u32 ctrl_reg;
ctrl_reg = readl_relaxed(timer->base_addr + TTC_CNT_CNTRL_OFFSET);
ctrl_reg &= ~TTC_CNT_CNTRL_DISABLE_MASK;
writel_relaxed(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET);
return 0;
}
static int ttc_rate_change_clocksource_cb(struct notifier_block *nb,
unsigned long event, void *data)
{
struct clk_notifier_data *ndata = data;
struct ttc_timer *ttc = to_ttc_timer(nb);
struct ttc_timer_clocksource *ttccs = container_of(ttc,
struct ttc_timer_clocksource, ttc);
switch (event) {
case PRE_RATE_CHANGE:
{
u32 psv;
unsigned long factor, rate_low, rate_high;
if (ndata->new_rate > ndata->old_rate) {
factor = DIV_ROUND_CLOSEST(ndata->new_rate,
ndata->old_rate);
rate_low = ndata->old_rate;
rate_high = ndata->new_rate;
} else {
factor = DIV_ROUND_CLOSEST(ndata->old_rate,
ndata->new_rate);
rate_low = ndata->new_rate;
rate_high = ndata->old_rate;
}
if (!is_power_of_2(factor))
return NOTIFY_BAD;
if (abs(rate_high - (factor * rate_low)) > MAX_F_ERR)
return NOTIFY_BAD;
factor = __ilog2_u32(factor);
/*
* store timer clock ctrl register so we can restore it in case
* of an abort.
*/
ttccs->scale_clk_ctrl_reg_old =
readl_relaxed(ttccs->ttc.base_addr +
TTC_CLK_CNTRL_OFFSET);
psv = (ttccs->scale_clk_ctrl_reg_old &
TTC_CLK_CNTRL_PSV_MASK) >>
TTC_CLK_CNTRL_PSV_SHIFT;
if (ndata->new_rate < ndata->old_rate)
psv -= factor;
else
psv += factor;
/* prescaler within legal range? */
if (psv & ~(TTC_CLK_CNTRL_PSV_MASK >> TTC_CLK_CNTRL_PSV_SHIFT))
return NOTIFY_BAD;
ttccs->scale_clk_ctrl_reg_new = ttccs->scale_clk_ctrl_reg_old &
~TTC_CLK_CNTRL_PSV_MASK;
ttccs->scale_clk_ctrl_reg_new |= psv << TTC_CLK_CNTRL_PSV_SHIFT;
/* scale down: adjust divider in post-change notification */
if (ndata->new_rate < ndata->old_rate)
return NOTIFY_DONE;
/* scale up: adjust divider now - before frequency change */
writel_relaxed(ttccs->scale_clk_ctrl_reg_new,
ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
break;
}
case POST_RATE_CHANGE:
/* scale up: pre-change notification did the adjustment */
if (ndata->new_rate > ndata->old_rate)
return NOTIFY_OK;
/* scale down: adjust divider now - after frequency change */
writel_relaxed(ttccs->scale_clk_ctrl_reg_new,
ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
break;
case ABORT_RATE_CHANGE:
/* we have to undo the adjustment in case we scale up */
|