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Date: Tue, 13 Jun 2017 15:54:24 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Dong Aisheng <aisheng.dong@....com>, linux-kernel@...r.kernel.org
Cc: linux-arm-kernel@...ts.infradead.org, tglx@...utronix.de,
shawnguo@...nel.org, ping.bai@....com, anson.huang@....com,
dongas86@...il.com, kernel@...gutronix.de, arnd@...db.de
Subject: Re: [PATCH V2 2/2] timer: imx-tpm: add imx tpm timer support
On 13/06/2017 09:58, Dong Aisheng wrote:
> IMX Timer/PWM Module (TPM) supports both timer and pwm function while
> this patch only adds the timer support. PWM would be added later.
>
> The TPM counter, compare and capture registers are clocked by an
> asynchronous clock that can remain enabled in low power modes.
>
> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Shawn Guo <shawnguo@...nel.org>
> Cc: Anson Huang <Anson.Huang@....com>
> Cc: Bai Ping <ping.bai@....com>
> Signed-off-by: Dong Aisheng <aisheng.dong@....com>
>
> ---
nitpicking comments below.
Other than that sounds ok for me.
> ChangeLog:
> v1->v2:
> * change to readl/writel from __raw_readl/writel according to Arnd's
> suggestion to avoid endian issue
> * add help information in Kconfig
> * add more error checking
> ---
> drivers/clocksource/Kconfig | 8 ++
> drivers/clocksource/Makefile | 1 +
> drivers/clocksource/timer-imx-tpm.c | 227 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 236 insertions(+)
> create mode 100644 drivers/clocksource/timer-imx-tpm.c
>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 545d541..33b4d31 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -603,6 +603,14 @@ config CLKSRC_IMX_GPT
> depends on ARM && CLKDEV_LOOKUP
> select CLKSRC_MMIO
>
> +config CLKSRC_IMX_TPM
> + bool "Clocksource using i.MX TPM" if COMPILE_TEST
> + depends on ARM && CLKDEV_LOOKUP && GENERIC_CLOCKEVENTS
> + select CLKSRC_MMIO
> + help
> + Enable this option to use IMX Timer/PWM Module (TPM) timer as
> + clocksource.
> +
> config CLKSRC_ST_LPC
> bool "Low power clocksource found in the LPC" if COMPILE_TEST
> select CLKSRC_OF if OF
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 2b5b56a..9fdf8da0 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -67,6 +67,7 @@ obj-$(CONFIG_CLKSRC_VERSATILE) += versatile.o
> obj-$(CONFIG_CLKSRC_MIPS_GIC) += mips-gic-timer.o
> obj-$(CONFIG_CLKSRC_TANGO_XTAL) += tango_xtal.o
> obj-$(CONFIG_CLKSRC_IMX_GPT) += timer-imx-gpt.o
> +obj-$(CONFIG_CLKSRC_IMX_TPM) += timer-imx-tpm.o
> obj-$(CONFIG_ASM9260_TIMER) += asm9260_timer.o
> obj-$(CONFIG_H8300_TMR8) += h8300_timer8.o
> obj-$(CONFIG_H8300_TMR16) += h8300_timer16.o
> diff --git a/drivers/clocksource/timer-imx-tpm.c b/drivers/clocksource/timer-imx-tpm.c
> new file mode 100644
> index 0000000..940a4f75
> --- /dev/null
> +++ b/drivers/clocksource/timer-imx-tpm.c
> @@ -0,0 +1,227 @@
> +/*
> + * Copyright 2016 Freescale Semiconductor, Inc.
> + * Copyright 2017 NXP
> + *
> + * 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/clk.h>
> +#include <linux/clockchips.h>
> +#include <linux/clocksource.h>
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/sched_clock.h>
> +
> +#define TPM_SC 0x10
> +#define TPM_SC_CMOD_INC_PER_CNT (0x1 << 3)
> +#define TPM_SC_CMOD_DIV_DEFAULT 0x3
> +#define TPM_CNT 0x14
> +#define TPM_MOD 0x18
> +#define TPM_STATUS 0x1c
> +#define TPM_STATUS_CH0F BIT(0)
> +#define TPM_C0SC 0x20
> +#define TPM_C0SC_CHIE BIT(6)
> +#define TPM_C0SC_MODE_SHIFT 2
> +#define TPM_C0SC_MODE_MASK 0x3c
> +#define TPM_C0SC_MODE_SW_COMPARE 0x4
> +#define TPM_C0V 0x24
> +
> +static void __iomem *timer_base;
> +static struct clock_event_device clockevent_tpm;
> +
> +static inline void tpm_timer_disable(void)
> +{
> + unsigned int val;
> +
> + /* channel disable */
> + val = readl(timer_base + TPM_C0SC);
> + val &= ~(TPM_C0SC_MODE_MASK | TPM_C0SC_CHIE);
> + writel(val, timer_base + TPM_C0SC);
> +}
> +
> +static inline void tpm_timer_enable(void)
> +{
> + unsigned int val;
> +
> + /* channel enabled in sw compare mode */
> + val = readl(timer_base + TPM_C0SC);
> + val |= (TPM_C0SC_MODE_SW_COMPARE << TPM_C0SC_MODE_SHIFT) |
> + TPM_C0SC_CHIE;
> + writel(val, timer_base + TPM_C0SC);
> +}
> +
> +static inline void tpm_irq_acknowledge(void)
> +{
> + writel(TPM_STATUS_CH0F, timer_base + TPM_STATUS);
> +}
> +
> +static struct delay_timer tpm_delay_timer;
static inline unsigned long tpm_read_counter(void)
{
readl(timer_base + TPM_CNT);
}
static unsigned long tpm_read_current_timer(void)
{
return tpm_read_counter();
}
static u64 notrace tpm_read_sched_clock(void)
{
return tpm_read_counter();
}
> +
> +static unsigned long tpm_read_current_timer(void)
> +{
> + return readl(timer_base + TPM_CNT);
> +}
> +
> +static u64 notrace tpm_read_sched_clock(void)
> +{
> + return readl(timer_base + TPM_CNT);
> +}
> +
> +static int __init tpm_clocksource_init(unsigned long rate)
> +{
> + tpm_delay_timer.read_current_timer = &tpm_read_current_timer;
> + tpm_delay_timer.freq = rate;
> + register_current_timer_delay(&tpm_delay_timer);
> +
> + sched_clock_register(tpm_read_sched_clock, 32, rate);
> +
> + return clocksource_mmio_init(timer_base + TPM_CNT, "imx-tpm",
> + rate, 200, 32, clocksource_mmio_readl_up);
> +}
> +
> +static int tpm_set_next_event(unsigned long delta,
> + struct clock_event_device *evt)
> +{
> + unsigned long next, now;
> +
> + next = readl(timer_base + TPM_CNT) + delta;
> + writel(next, timer_base + TPM_C0V);
> + now = readl(timer_base + TPM_CNT);
s/readl(..)/tpm_read_counter()/
> +
> + return (int)((next - now) <= 0) ? -ETIME : 0;
Are you sure about this?
The following thread will help to sort it out:
http://lists.infradead.org/pipermail/linux-arm-kernel/2016-January/397287.html
A simple program with a nanosleep with a very small delta should spot
the issue immediately.
> +}
> +
> +static int tpm_set_state_oneshot(struct clock_event_device *evt)
> +{
> + tpm_timer_enable();
> +
> + return 0;
> +}
> +
> +static int tpm_set_state_shutdown(struct clock_event_device *evt)
> +{
> + tpm_timer_disable();
> +
> + return 0;
> +}
> +
> +static irqreturn_t tpm_timer_interrupt(int irq, void *dev_id)
> +{
> + struct clock_event_device *evt = &clockevent_tpm;
struct clock_event_device *evt = dev_id;
> +
> + tpm_irq_acknowledge();
> +
> + evt->event_handler(evt);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static struct clock_event_device clockevent_tpm = {
> + .name = "i.MX7ULP TPM Timer",
> + .features = CLOCK_EVT_FEAT_ONESHOT,
> + .set_state_oneshot = tpm_set_state_oneshot,
> + .set_next_event = tpm_set_next_event,
> + .set_state_shutdown = tpm_set_state_shutdown,
> + .rating = 200,
> +};
> +
> +static struct irqaction tpm_timer_irq = {
> + .name = "i.MX7ULP TPM Timer",
> + .flags = IRQF_TIMER | IRQF_IRQPOLL,
> + .handler = tpm_timer_interrupt,
> + .dev_id = &clockevent_tpm,
> +};
> +
> +static int __init tpm_clockevent_init(unsigned long rate, int irq)
> +{
> + setup_irq(irq, &tpm_timer_irq);
> +
> + clockevent_tpm.cpumask = cpumask_of(0);
> + clockevent_tpm.irq = irq;
> + clockevents_config_and_register(&clockevent_tpm,
> + rate, 0xff, 0xfffffffe);
> +
> + return 0;
> +}
> +
> +static int __init tpm_timer_init(struct device_node *np)
> +{
> + struct clk *ipg, *per;
> + int irq, ret;
> + u32 rate;
> +
> + timer_base = of_iomap(np, 0);
> + if (!timer_base) {
> + pr_err("tpm: failed to get base address\n");
> + return -ENXIO;
> + }
> +
> + irq = irq_of_parse_and_map(np, 0);
> + if (!irq) {
> + pr_err("tpm: failed to get irq\n");
> + ret = -ENOENT;
> + goto err_iomap;
> + }
> +
> + ipg = of_clk_get_by_name(np, "ipg");
> + per = of_clk_get_by_name(np, "per");
> + if (IS_ERR(ipg) || IS_ERR(per)) {
> + pr_err("tpm: failed to get igp or per clk\n");
> + ret = -ENODEV;
> + goto err_clk_get;
> + }
> +
> + /* enable clk before accessing registers */
> + ret = clk_prepare_enable(ipg);
> + if (ret) {
> + pr_err("tpm: ipg clock enable failed (%d)\n", ret);
> + goto err_ipg_clk_enable;
> + }
> +
> + ret = clk_prepare_enable(per);
> + if (ret) {
> + pr_err("tpm: per clock enable failed (%d)\n", ret);
> + goto err_per_clk_enable;
> + }
> +
> + /*
> + * Initialize tpm module to a known state
> + * 1) Counter disabled
> + * 2) TPM counter operates in up counting mode
> + * 3) Timer Overflow Interrupt disabled
> + * 4) Channel0 disabled
> + * 5) DMA transfers disabled
> + */
> + writel(0, timer_base + TPM_SC);
> + writel(0, timer_base + TPM_CNT);
> + writel(0, timer_base + TPM_C0SC);
> +
> + /* increase per cnt, div 8 by default */
> + writel(TPM_SC_CMOD_INC_PER_CNT | TPM_SC_CMOD_DIV_DEFAULT,
> + timer_base + TPM_SC);
> +
> + /* set MOD register to maximum for free running mode */
> + writel(0xffffffff, timer_base + TPM_MOD);
> +
> + rate = clk_get_rate(per) / 8;
rate = clk_get_rate(per) >> 3;
> + tpm_clocksource_init(rate);
> + tpm_clockevent_init(rate, irq);
> +
> + return 0;
> +
> +err_per_clk_enable:
> + clk_disable_unprepare(ipg);
> +err_ipg_clk_enable:
> +err_clk_get:
> + clk_put(per);
> + clk_put(ipg);
> +err_iomap:
> + iounmap(timer_base);
> + return ret;
> +}
> +CLOCKSOURCE_OF_DECLARE(imx7ulp, "fsl,imx7ulp-tpm", tpm_timer_init);
>
--
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