/*
* Copyright (C) 2014 Oleksij Rempel <linux@rempel-privat.de>
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/bitops.h>
#define DRIVER_NAME "asm9260-timer"
/*
* this device provide 4 offsets for each register:
* 0x0 - plain read write mode
* 0x4 - set mode, OR logic.
* 0x8 - clr mode, XOR logic.
* 0xc - togle mode.
*/
#define SET_REG 4
#define CLR_REG 8
#define HW_IR 0x0000 /* RW. Interrupt */
#define BM_IR_CR0 BIT(4)
#define BM_IR_MR3 BIT(3)
#define BM_IR_MR2 BIT(2)
#define BM_IR_MR1 BIT(1)
#define BM_IR_MR0 BIT(0)
#define HW_TCR 0x0010 /* RW. Timer controller */
/* BM_C*_RST
* Timer Counter and the Prescale Counter are synchronously reset on the
* next positive edge of PCLK. The counters remain reset until TCR[1] is
* returned to zero. */
#define BM_C3_RST BIT(7)
#define BM_C2_RST BIT(6)
#define BM_C1_RST BIT(5)
#define BM_C0_RST BIT(4)
/* BM_C*_EN
* 1 - Timer Counter and Prescale Counter are enabled for counting
* 0 - counters are disabled */
#define BM_C3_EN BIT(3)
#define BM_C2_EN BIT(2)
#define BM_C1_EN BIT(1)
#define BM_C0_EN BIT(0)
#define HW_DIR 0x0020 /* RW. Direction? */
/* 00 - count up
* 01 - count down
* 10 - ?? 2^n/2 */
#define BM_DIR_COUNT_UP 0
#define BM_DIR_COUNT_DOWN 1
#define BM_DIR0_SHIFT 0
#define BM_DIR1_SHIFT 4
#define BM_DIR2_SHIFT 8
#define BM_DIR3_SHIFT 12
#define BM_DIR_DEFAULT (BM_DIR_COUNT_UP << BM_DIR0_SHIFT | \
BM_DIR_COUNT_UP << BM_DIR1_SHIFT | \
BM_DIR_COUNT_UP << BM_DIR2_SHIFT | \
BM_DIR_COUNT_UP << BM_DIR3_SHIFT)
#define HW_TC0 0x0030 /* RO. Timer counter 0 */
/* HW_TC*. Timer counter owerflow (0xffff.ffff to 0x0000.0000) do not generate
* interrupt. This registers can be used to detect overflow */
#define HW_TC1 0x0040
#define HW_TC2 0x0050
#define HW_TC3 0x0060
#define HW_PR 0x0070 /* RW. prescaler */
#define BM_PR_DISABLE 0
#define HW_PC 0x0080 /* RO. Prescaler counter */
#define HW_MCR 0x0090 /* RW. Match control */
/* enable interrupt on match */
#define BM_MCR_INT_EN(n) (1 << (n * 3 + 0))
/* enable TC reset on match */
#define BM_MCR_RES_EN(n) (1 << (n * 3 + 1))
/* enable stop TC on match */
#define BM_MCR_STOP_EN(n) (1 << (n * 3 + 2))
#define HW_MR0 0x00a0 /* RW. Match reg */
#define HW_MR1 0x00b0
#define HW_MR2 0x00C0
#define HW_MR3 0x00D0
#define HW_CTCR 0x0180 /* Counter control */
#define BM_CTCR0_SHIFT 0
#define BM_CTCR1_SHIFT 2
#define BM_CTCR2_SHIFT 4
#define BM_CTCR3_SHIFT 6
#define BM_CTCR_TM 0 /* Timer mode. Every rising PCLK edge. */
#define BM_CTCR_DEFAULT (BM_CTCR_TM << BM_CTCR0_SHIFT | \
BM_CTCR_TM << BM_CTCR1_SHIFT | \
BM_CTCR_TM << BM_CTCR2_SHIFT | \
BM_CTCR_TM << BM_CTCR3_SHIFT)
static struct asm9260_timer_priv {
void __iomem *base;
unsigned long ticks_per_jiffy;
} priv;
static int asm9260_timer_set_next_event(unsigned long delta,
struct clock_event_device *evt)
{
/* configure match count for TC0 */
writel_relaxed(delta, priv.base + HW_MR0);
/* enable TC0 */
writel_relaxed(BM_C0_EN, priv.base + HW_TCR + SET_REG);
return 0;
}
static void asm9260_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
/* stop timer0 */
writel_relaxed(BM_C0_EN, priv.base + HW_TCR + CLR_REG);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
/* disable reset and stop on match */
writel_relaxed(BM_MCR_RES_EN(0) | BM_MCR_STOP_EN(0),
priv.base + HW_MCR + CLR_REG);
/* configure match count for TC0 */
writel_relaxed(priv.ticks_per_jiffy, priv.base + HW_MR0);
/* enable TC0 */
writel_relaxed(BM_C0_EN, priv.base + HW_TCR + SET_REG);
break;
case CLOCK_EVT_MODE_ONESHOT:
/* enable reset and stop on match */
writel_relaxed(BM_MCR_RES_EN(0) | BM_MCR_STOP_EN(0),
priv.base + HW_MCR + SET_REG);
break;
default:
break;
}
}
static struct clock_event_device event_dev = {
.name = DRIVER_NAME,
.rating = 200,
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.set_next_event = asm9260_timer_set_next_event,
.set_mode = asm9260_timer_set_mode,
};
static irqreturn_t asm9260_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
evt->event_handler(evt);
writel_relaxed(BM_IR_MR0, priv.base + HW_IR);
return IRQ_HANDLED;
}
/*
* ---------------------------------------------------------------------------
* Timer initialization
* ---------------------------------------------------------------------------
*/
static void __init asm9260_timer_init(struct device_node *np)
{
int irq;
struct clk *clk;
int ret;
unsigned long rate;
priv.base = of_io_request_and_map(np, 0, np->name);
if (!priv.base)
panic("%s: unable to map resource", np->name);
clk = of_clk_get(np, 0);
ret = clk_prepare_enable(clk);
if (ret)
panic("Failed to enable clk!\n");
irq = irq_of_parse_and_map(np, 0);
ret = request_irq(irq, asm9260_timer_interrupt, IRQF_TIMER,
DRIVER_NAME, &event_dev);
if (ret)
panic("Failed to setup irq!\n");
/* set all timers for count-up */
writel_relaxed(BM_DIR_DEFAULT, priv.base + HW_DIR);
/* disable divider */
writel_relaxed(BM_PR_DISABLE, priv.base + HW_PR);
/* make sure all timers use every rising PCLK edge. */
writel_relaxed(BM_CTCR_DEFAULT, priv.base + HW_CTCR);
/* enable interrupt for TC0 and clean setting for all other lines */
writel_relaxed(BM_MCR_INT_EN(0) , priv.base + HW_MCR);
rate = clk_get_rate(clk);
clocksource_mmio_init(priv.base + HW_TC1, DRIVER_NAME, rate,
200, 32, clocksource_mmio_readl_up);
/* Seems like we can't use counter without match register even if
* actions for MR are disabled. So, set MR to max value. */
writel_relaxed(0xffffffff, priv.base + HW_MR1);
/* enable TC1 */
writel_relaxed(BM_C1_EN, priv.base + HW_TCR + SET_REG);
priv.ticks_per_jiffy = DIV_ROUND_CLOSEST(rate, HZ);
event_dev.cpumask = cpumask_of(0);
clockevents_config_and_register(&event_dev, rate, 0x2c00, 0xfffffffe);
}
CLOCKSOURCE_OF_DECLARE(asm9260_timer, "alphascale,asm9260-timer",
asm9260_timer_init);