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Date: Fri, 8 Dec 2017 07:58:51 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Baolin Wang <baolin.wang@...eadtrum.com>, tglx@...utronix.de,
robh+dt@...nel.org, mark.rutland@....com
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
broonie@...nel.org, baolin.wang@...aro.org
Subject: Re: [PATCH v3 2/2] clocksource: sprd: Add timer driver for Spreadtrum
SC9860 platform
On 08/12/2017 06:03, Baolin Wang wrote:
> The Spreadtrum SC9860 platform will use the architected timers as local
> clock events, but we also need a broadcast timer device to wakeup the
> cpus when the cpus are in sleep mode.
>
> The Spreadtrum timer can support 32bit or 64bit counter, as well as
> supporting period mode or one-shot mode.
>
> Signed-off-by: Baolin Wang <baolin.wang@...eadtrum.com>
> ---
> Changes since v2:
> - Add more timer description in changelog.
> - Rename the driver file.
> - Remove GENERIC_CLOCKEVENTS and ARCH_SPRD dependency.
> - Remove some redundant headfiles.
> - Use timer-of APIs.
> - Change the license format according to Linus[1][2][3],
> Thomas[4] and Greg[5] comments on the topic.
> [1] https://lkml.org/lkml/2017/11/2/715
> [2] https://lkml.org/lkml/2017/11/25/125
> [3] https://lkml.org/lkml/2017/11/25/133
> [4] https://lkml.org/lkml/2017/11/2/805
> [5] https://lkml.org/lkml/2017/10/19/165
>
> Changes since v1:
> - Change to 32bit counter to avoid build warning.
> ---
> drivers/clocksource/Kconfig | 7 ++
> drivers/clocksource/Makefile | 1 +
> drivers/clocksource/timer-sprd.c | 168 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 176 insertions(+)
> create mode 100644 drivers/clocksource/timer-sprd.c
>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index c729a88..9a6b087 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -441,6 +441,13 @@ config MTK_TIMER
> help
> Support for Mediatek timer driver.
>
> +config SPRD_TIMER
> + bool "Spreadtrum timer driver" if COMPILE_TEST
> + depends on HAS_IOMEM
> + select TIMER_OF
> + help
> + Enables the support for the Spreadtrum timer driver.
> +
> config SYS_SUPPORTS_SH_MTU2
> bool
>
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 72711f1..d6dec44 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_CLKSRC_TI_32K) += timer-ti-32k.o
> obj-$(CONFIG_CLKSRC_NPS) += timer-nps.o
> obj-$(CONFIG_OXNAS_RPS_TIMER) += timer-oxnas-rps.o
> obj-$(CONFIG_OWL_TIMER) += owl-timer.o
> +obj-$(CONFIG_SPRD_TIMER) += timer-sprd.o
>
> obj-$(CONFIG_ARC_TIMERS) += arc_timer.o
> obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
> diff --git a/drivers/clocksource/timer-sprd.c b/drivers/clocksource/timer-sprd.c
> new file mode 100644
> index 0000000..81a5f0c
> --- /dev/null
> +++ b/drivers/clocksource/timer-sprd.c
> @@ -0,0 +1,168 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2017 Spreadtrum Communications Inc.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +
> +#include "timer-of.h"
> +
> +#define TIMER_NAME "sprd_timer"
> +
> +#define TIMER_LOAD_LO 0x0
> +#define TIMER_LOAD_HI 0x4
> +#define TIMER_VALUE_LO 0x8
> +#define TIMER_VALUE_HI 0xc
> +
> +#define TIMER_CTL 0x10
> +#define TIMER_CTL_PERIOD_MODE BIT(0)
> +#define TIMER_CTL_ENABLE BIT(1)
> +#define TIMER_CTL_64BIT_WIDTH BIT(16)
> +
> +#define TIMER_INT 0x14
> +#define TIMER_INT_EN BIT(0)
> +#define TIMER_INT_RAW_STS BIT(1)
> +#define TIMER_INT_MASK_STS BIT(2)
> +#define TIMER_INT_CLR BIT(3)
> +
> +#define TIMER_VALUE_SHDW_LO 0x18
> +#define TIMER_VALUE_SHDW_HI 0x1c
> +
> +#define TIMER_VALUE_LO_MASK GENMASK(31, 0)
> +
> +static void sprd_timer_enable(void __iomem *base, u32 flag)
> +{
> + u32 val = readl_relaxed(base + TIMER_CTL);
> +
> + val |= TIMER_CTL_ENABLE;
> + if (flag & TIMER_CTL_64BIT_WIDTH)
> + val |= TIMER_CTL_64BIT_WIDTH;
> + else
> + val &= ~TIMER_CTL_64BIT_WIDTH;
> +
> + if (flag & TIMER_CTL_PERIOD_MODE)
> + val |= TIMER_CTL_PERIOD_MODE;
> + else
> + val &= ~TIMER_CTL_PERIOD_MODE;
> +
> + writel_relaxed(val, base + TIMER_CTL);
> +}
> +
> +static void sprd_timer_disable(void __iomem *base)
> +{
> + u32 val = readl_relaxed(base + TIMER_CTL);
> +
> + val &= ~TIMER_CTL_ENABLE;
> + writel_relaxed(val, base + TIMER_CTL);
> +}
> +
> +static void sprd_timer_update_counter(void __iomem *base, unsigned long cycles)
> +{
> + writel_relaxed(cycles & TIMER_VALUE_LO_MASK, base + TIMER_LOAD_LO);
> + writel_relaxed(0, base + TIMER_LOAD_HI);
> +}
> +
> +static void sprd_timer_enable_interrupt(void __iomem *base)
> +{
> + writel_relaxed(TIMER_INT_EN, base + TIMER_INT);
> +}
> +
> +static void sprd_timer_clear_interrupt(void __iomem *base)
> +{
> + u32 val = readl_relaxed(base + TIMER_INT);
> +
> + val |= TIMER_INT_CLR;
> + writel_relaxed(val, base + TIMER_INT);
> +}
> +
> +static int sprd_timer_set_next_event(unsigned long cycles,
> + struct clock_event_device *ce)
> +{
> + struct timer_of *to = to_timer_of(ce);
> +
> + sprd_timer_disable(timer_of_base(to));
> + sprd_timer_update_counter(timer_of_base(to), cycles);
> + sprd_timer_enable(timer_of_base(to), 0);
> +
> + return 0;
> +}
> +
> +static int sprd_timer_set_periodic(struct clock_event_device *ce)
> +{
> + struct timer_of *to = to_timer_of(ce);
> +
> + sprd_timer_disable(timer_of_base(to));
> + sprd_timer_update_counter(timer_of_base(to), timer_of_period(to));
> + sprd_timer_enable(timer_of_base(to), TIMER_CTL_PERIOD_MODE);
> +
> + return 0;
> +}
> +
> +static int sprd_timer_shutdown(struct clock_event_device *ce)
> +{
> + struct timer_of *to = to_timer_of(ce);
> +
> + sprd_timer_disable(timer_of_base(to));
> + return 0;
> +}
> +
> +static irqreturn_t sprd_timer_interrupt(int irq, void *dev_id)
> +{
> + struct clock_event_device *ce = (struct clock_event_device *)dev_id;
> + struct timer_of *to = to_timer_of(ce);
> +
> + sprd_timer_clear_interrupt(timer_of_base(to));
> +
> + if (clockevent_state_oneshot(ce))
> + sprd_timer_disable(timer_of_base(to));
> +
> + ce->event_handler(ce);
> + return IRQ_HANDLED;
> +}
> +
> +static struct timer_of to = {
> + .flags = TIMER_OF_IRQ | TIMER_OF_BASE,
Why not the TIMER_OF_CLOCK ?
> +
> + .clkevt = {
> + .name = TIMER_NAME,
> + .rating = 300,
> + .features = CLOCK_EVT_FEAT_DYNIRQ | CLOCK_EVT_FEAT_PERIODIC |
> + CLOCK_EVT_FEAT_ONESHOT,
> + .set_state_shutdown = sprd_timer_shutdown,
> + .set_state_periodic = sprd_timer_set_periodic,
> + .set_next_event = sprd_timer_set_next_event,
> + .cpumask = cpu_possible_mask,
> + },
> +
> + .of_irq = {
> + .handler = sprd_timer_interrupt,
> + .flags = IRQF_TIMER | IRQF_IRQPOLL,
> + },
> +};
> +
> +static int __init sprd_timer_init(struct device_node *np)
> +{
> + int ret;
> + u32 freq;
> +
> + ret = timer_of_init(np, &to);
> + if (ret)
> + return ret;
> +
> + ret = of_property_read_u32(np, "clock-frequency", &freq);
> + if (ret) {
> + pr_err("failed to get clock frequency\n");
> + timer_of_cleanup(&to);
> + return ret;
> + }
> +
> + to.of_clk.period = DIV_ROUND_UP(freq, HZ);
> +
> + sprd_timer_enable_interrupt(timer_of_base(&to));
> + clockevents_config_and_register(&to.clkevt, freq, 1, UINT_MAX);
> +
> + return 0;
> +}
> +
> +TIMER_OF_DECLARE(sc9860_timer, "sprd,sc9860-timer", sprd_timer_init);
>
--
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