Date:   Wed, 15 Jan 2020 14:44:37 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Paul Cercueil <paul@...pouillou.net>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     od@...c.me, linux-kernel@...r.kernel.org,
        Maarten ter Huurne <maarten@...ewalker.org>,
        Mathieu Malaterre <malat@...ian.org>,
        Artur Rojek <contact@...ur-rojek.eu>
Subject: Re: [PATCH v3] clocksource: Add driver for the Ingenic JZ47xx OST

On 14/01/2020 16:06, Paul Cercueil wrote:
> From: Maarten ter Huurne <maarten@...ewalker.org>
> 
> OST is the OS Timer, a 64-bit timer/counter with buffered reading.
> 
> SoCs before the JZ4770 had (if any) a 32-bit OST; the JZ4770 and
> JZ4780 have a 64-bit OST.
> 
> This driver will register both a clocksource and a sched_clock to the
> system.

Is the JZ47xx OST really a mfd needing a regmap? (Note regmap_read will
take a lock).


> Signed-off-by: Maarten ter Huurne <maarten@...ewalker.org>
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> Tested-by: Mathieu Malaterre <malat@...ian.org>
> Tested-by: Artur Rojek <contact@...ur-rojek.eu>
> ---
> 
> Notes:
>     v2: local_irq_save/restore were moved within sched_clock_register
>     v3: Only register as 32-bit clocksource to simplify things
> 
>  drivers/clocksource/Kconfig       |   8 ++
>  drivers/clocksource/Makefile      |   1 +
>  drivers/clocksource/ingenic-ost.c | 183 ++++++++++++++++++++++++++++++
>  3 files changed, 192 insertions(+)
>  create mode 100644 drivers/clocksource/ingenic-ost.c
> 
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 5fdd76cb1768..5be2f876f64f 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -697,4 +697,12 @@ config INGENIC_TIMER
>  	help
>  	  Support for the timer/counter unit of the Ingenic JZ SoCs.
>  
> +config INGENIC_OST
> +	bool "Ingenic JZ47xx Operating System Timer"
> +	depends on MIPS || COMPILE_TEST
> +	depends on COMMON_CLK
> +	select MFD_SYSCON
> +	help
> +	  Support for the OS Timer of the Ingenic JZ4770 or similar SoC.
> +
>  endmenu
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 4dfe4225ece7..6bc97a6fd229 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -80,6 +80,7 @@ obj-$(CONFIG_ASM9260_TIMER)		+= asm9260_timer.o
>  obj-$(CONFIG_H8300_TMR8)		+= h8300_timer8.o
>  obj-$(CONFIG_H8300_TMR16)		+= h8300_timer16.o
>  obj-$(CONFIG_H8300_TPU)			+= h8300_tpu.o
> +obj-$(CONFIG_INGENIC_OST)		+= ingenic-ost.o
>  obj-$(CONFIG_INGENIC_TIMER)		+= ingenic-timer.o
>  obj-$(CONFIG_CLKSRC_ST_LPC)		+= clksrc_st_lpc.o
>  obj-$(CONFIG_X86_NUMACHIP)		+= numachip.o
> diff --git a/drivers/clocksource/ingenic-ost.c b/drivers/clocksource/ingenic-ost.c
> new file mode 100644
> index 000000000000..2c91e3b34572
> --- /dev/null
> +++ b/drivers/clocksource/ingenic-ost.c
> @@ -0,0 +1,183 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * JZ47xx SoCs TCU Operating System Timer driver
> + *
> + * Copyright (C) 2016 Maarten ter Huurne <maarten@...ewalker.org>
> + * Copyright (C) 2020 Paul Cercueil <paul@...pouillou.net>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clocksource.h>
> +#include <linux/mfd/ingenic-tcu.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm.h>
> +#include <linux/regmap.h>
> +#include <linux/sched_clock.h>
> +
> +#define TCU_OST_TCSR_MASK	0xffc0
> +#define TCU_OST_TCSR_CNT_MD	BIT(15)
> +
> +#define TCU_OST_CHANNEL		15
> +
> +struct ingenic_ost_soc_info {
> +	bool is64bit;
> +};
> +
> +struct ingenic_ost {
> +	struct regmap *map;
> +	struct clk *clk;
> +
> +	struct clocksource cs;
> +};
> +
> +static struct ingenic_ost *ingenic_ost;
> +
> +static u64 notrace ingenic_ost_read_cntl(void)
> +{
> +	u32 val;
> +
> +	regmap_read(ingenic_ost->map, TCU_REG_OST_CNTL, &val);
> +
> +	return val;
> +}
> +
> +static u64 notrace ingenic_ost_read_cnth(void)
> +{
> +	u32 val;
> +
> +	regmap_read(ingenic_ost->map, TCU_REG_OST_CNTH, &val);
> +
> +	return val;
> +}
> +
> +static u64 notrace ingenic_ost_clocksource_readl(struct clocksource *cs)
> +{
> +	return ingenic_ost_read_cntl();
> +}
> +
> +static u64 notrace ingenic_ost_clocksource_readh(struct clocksource *cs)
> +{
> +	return ingenic_ost_read_cnth();
> +}
> +
> +static int __init ingenic_ost_probe(struct platform_device *pdev)
> +{
> +	const struct ingenic_ost_soc_info *soc_info;
> +	struct device *dev = &pdev->dev;
> +	struct ingenic_ost *ost;
> +	struct clocksource *cs;
> +	unsigned long rate;
> +	int err;
> +
> +	soc_info = device_get_match_data(dev);
> +	if (!soc_info)
> +		return -EINVAL;
> +
> +	ost = devm_kzalloc(dev, sizeof(*ost), GFP_KERNEL);
> +	if (!ost)
> +		return -ENOMEM;
> +
> +	ingenic_ost = ost;
> +
> +	ost->map = device_node_to_regmap(dev->parent->of_node);
> +	if (!ost->map) {
> +		dev_err(dev, "regmap not found\n");
> +		return -EINVAL;
> +	}
> +
> +	ost->clk = devm_clk_get(dev, "ost");
> +	if (IS_ERR(ost->clk))
> +		return PTR_ERR(ost->clk);
> +
> +	err = clk_prepare_enable(ost->clk);
> +	if (err)
> +		return err;
> +
> +	/* Clear counter high/low registers */
> +	if (soc_info->is64bit)
> +		regmap_write(ost->map, TCU_REG_OST_CNTL, 0);
> +	regmap_write(ost->map, TCU_REG_OST_CNTH, 0);
> +
> +	/* Don't reset counter at compare value. */
> +	regmap_update_bits(ost->map, TCU_REG_OST_TCSR,
> +			   TCU_OST_TCSR_MASK, TCU_OST_TCSR_CNT_MD);
> +
> +	rate = clk_get_rate(ost->clk);
> +
> +	/* Enable OST TCU channel */
> +	regmap_write(ost->map, TCU_REG_TESR, BIT(TCU_OST_CHANNEL));
> +
> +	cs = &ost->cs;
> +	cs->name	= "ingenic-ost";
> +	cs->rating	= 320;
> +	cs->flags	= CLOCK_SOURCE_IS_CONTINUOUS;
> +	cs->mask	= CLOCKSOURCE_MASK(32);
> +
> +	if (soc_info->is64bit)
> +		cs->read = ingenic_ost_clocksource_readl;
> +	else
> +		cs->read = ingenic_ost_clocksource_readh;
> +
> +	err = clocksource_register_hz(cs, rate);
> +	if (err) {
> +		dev_err(dev, "clocksource registration failed: %d\n", err);
> +		clk_disable_unprepare(ost->clk);
> +		return err;
> +	}
> +
> +	if (soc_info->is64bit)
> +		sched_clock_register(ingenic_ost_read_cntl, 32, rate);
> +	else
> +		sched_clock_register(ingenic_ost_read_cnth, 32, rate);
> +	return 0;
> +}
> +
> +static int __maybe_unused ingenic_ost_suspend(struct device *dev)
> +{
> +	struct ingenic_ost *ost = dev_get_drvdata(dev);
> +
> +	clk_disable(ost->clk);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused ingenic_ost_resume(struct device *dev)
> +{
> +	struct ingenic_ost *ost = dev_get_drvdata(dev);
> +
> +	return clk_enable(ost->clk);
> +}
> +
> +static const struct dev_pm_ops __maybe_unused ingenic_ost_pm_ops = {
> +	/* _noirq: We want the OST clock to be gated last / ungated first */
> +	.suspend_noirq = ingenic_ost_suspend,
> +	.resume_noirq  = ingenic_ost_resume,
> +};
> +
> +static const struct ingenic_ost_soc_info jz4725b_ost_soc_info = {
> +	.is64bit = false,
> +};
> +
> +static const struct ingenic_ost_soc_info jz4770_ost_soc_info = {
> +	.is64bit = true,
> +};
> +
> +static const struct of_device_id ingenic_ost_of_match[] = {
> +	{ .compatible = "ingenic,jz4725b-ost", .data = &jz4725b_ost_soc_info, },
> +	{ .compatible = "ingenic,jz4770-ost", .data = &jz4770_ost_soc_info, },
> +	{ }
> +};
> +
> +static struct platform_driver ingenic_ost_driver = {
> +	.driver = {
> +		.name = "ingenic-ost",
> +#ifdef CONFIG_PM_SUSPEND
> +		.pm = &ingenic_ost_pm_ops,
> +#endif
> +		.of_match_table = ingenic_ost_of_match,
> +	},
> +};
> +builtin_platform_driver_probe(ingenic_ost_driver, ingenic_ost_probe);
> 


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