Re: [PATCH v12 07/13] clocksource: Add a new timer-ingenic driver

[Paul Cercueil <paul@crapouillou.net>]

Hi,

I'll make a V13 of this patchset on top of -rc6, any feedback
for this clocksource driver? It's been already one month.

Thanks,
-Paul



Le mar. 21 mai 2019 à 16:51, Paul Cercueil <paul@crapouillou.net> a 
écrit :
> This driver handles the TCU (Timer Counter Unit) present on the 
> Ingenic
> JZ47xx SoCs, and provides the kernel with a system timer, a 
> clocksource
> and a sched_clock.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
> 
> Notes:
>     v2: Use SPDX identifier for the license
> 
>     v3: - Move documentation to its own patch
>     	- Search the devicetree for PWM clients, and use all the TCU
>     	  channels that won't be used for PWM
> 
>     v4: - Add documentation about why we search for PWM clients
>     	- Verify that the PWM clients are for the TCU PWM driver
> 
>     v5: Major overhaul. Too many changes to list. Consider it's a new
>     	patch.
> 
>     v6: - Add two API functions ingenic_tcu_request_channel and
>     	  ingenic_tcu_release_channel. To be used by the PWM driver to
>     	  request the use of a TCU channel. The driver will now 
> dynamically
>     	  move away the system timer or clocksource to a new TCU channel.
>     	- The system timer now defaults to channel 0, the clocksource now
>     	  defaults to channel 1 and is no more optional. The
>     	  ingenic,timer-channel and ingenic,clocksource-channel 
> devicetree
>     	  properties are now gone.
>     	- Fix round_rate / set_rate not calculating the prescale divider
>     	  the same way. This caused problems when (parent_rate / div) 
> would
>     	  give a non-integer result. The behaviour is correct now.
>     	- The clocksource clock is turned off on suspend now.
> 
>     v7: Fix section mismatch by using builtin_platform_driver_probe()
> 
>     v8: - Removed ingenic_tcu_[request,release]_channel, and the 
> mechanism
>     	  to dynamically change the TCU channel of the system timer or
>     	  the clocksource.
>     	- The driver's devicetree node can now have two more children
>     	  nodes, that correspond to the system timer and clocksource.
>     	  For these two, the driver will use the TCU timer that
>     	  correspond to the memory resource supplied in their
>     	  respective node.
> 
>     v9: - Removed support for clocksource / timer children devicetree
>     	  nodes. Now, we use a property "ingenic,pwm-channels-mask" to
>     	  know which PWM channels are reserved for PWM use and should
>     	  not be used as OS timers.
> 
>     v10: - Use CLK_SET_RATE_UNGATE instead of CLK_SET_RATE_GATE + 
> manually
>     	   un-gating the clock before changing rate. Same for 
> re-parenting.
>     	 - Unconditionally create the clocksource and sched_clock even if
>     	   the SoC possesses a OS Timer. That gives the choice back to 
> the
>     	   user which clocksource should be selected.
>     	 - Use subsys_initcall() instead of 
> builtin_platform_driver_probe().
>     	   The OS Timer driver calls builtin_platform_driver_probe, which
>     	   requires the device to be created before that.
>     	 - Cosmetic cleanups
> 
>     v11: - Change prototype of exported function
>     	   ingenic_tcu_pwm_can_use_chn(), use a struct device * as first
>     	   argument.
>     	 - Read clocksource using the regmap instead of bypassing it.
>     	   Bypassing the regmap makes sense only for the sched_clock 
> where
>     	   the read operation must be as fast as possible.
>     	 - Fix incorrect format in pr_crit() macro
> 
>     v12: - Clock handling and IRQ handling are gone, and are now 
> handled
>     	   in their own driver.
>     	 - Obtain regmap from the ingenic-tcu MFD driver. As a result, we
>     	   cannot bypass the regmap anymore for the sched_clock.
> 
>  drivers/clocksource/Kconfig         |  11 +
>  drivers/clocksource/Makefile        |   1 +
>  drivers/clocksource/ingenic-timer.c | 357 
> ++++++++++++++++++++++++++++
>  3 files changed, 369 insertions(+)
>  create mode 100644 drivers/clocksource/ingenic-timer.c
> 
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 6bcaa4e2e72c..bb5d5c044341 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -672,4 +672,15 @@ config MILBEAUT_TIMER
>  	help
>  	  Enables the support for Milbeaut timer driver.
> 
> +config INGENIC_TIMER
> +	bool "Clocksource/timer using the TCU in Ingenic JZ SoCs"
> +	default MACH_INGENIC
> +	depends on MIPS || COMPILE_TEST
> +	depends on COMMON_CLK
> +	select INGENIC_TCU
> +	select TIMER_OF
> +	select IRQ_DOMAIN
> +	help
> +	  Support for the timer/counter unit of the Ingenic JZ SoCs.
> +
>  endmenu
> diff --git a/drivers/clocksource/Makefile 
> b/drivers/clocksource/Makefile
> index 236858fa7fbf..553f3c61717a 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -78,6 +78,7 @@ 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-$(CONFIG_INGENIC_TIMER)		+= ingenic-timer.o
>  obj-$(CONFIG_CLKSRC_ST_LPC)		+= clksrc_st_lpc.o
>  obj-$(CONFIG_X86_NUMACHIP)		+= numachip.o
>  obj-$(CONFIG_ATCPIT100_TIMER)		+= timer-atcpit100.o
> diff --git a/drivers/clocksource/ingenic-timer.c 
> b/drivers/clocksource/ingenic-timer.c
> new file mode 100644
> index 000000000000..9f4df64390f4
> --- /dev/null
> +++ b/drivers/clocksource/ingenic-timer.c
> @@ -0,0 +1,357 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * JZ47xx SoCs TCU IRQ driver
> + * Copyright (C) 2019 Paul Cercueil <paul@crapouillou.net>
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/clockchips.h>
> +#include <linux/clocksource.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/ingenic-tcu.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/sched_clock.h>
> +
> +#include <dt-bindings/clock/ingenic,tcu.h>
> +
> +struct ingenic_soc_info {
> +	unsigned int num_channels;
> +};
> +
> +struct ingenic_tcu {
> +	struct regmap *map;
> +	struct clk *timer_clk, *cs_clk;
> +
> +	unsigned int timer_channel, cs_channel;
> +	struct clock_event_device cevt;
> +	struct clocksource cs;
> +	char name[4];
> +
> +	unsigned long pwm_channels_mask;
> +};
> +
> +static struct ingenic_tcu *ingenic_tcu;
> +
> +static u64 notrace ingenic_tcu_timer_read(void)
> +{
> +	struct ingenic_tcu *tcu = ingenic_tcu;
> +	unsigned int count;
> +
> +	regmap_read(tcu->map, TCU_REG_TCNTc(tcu->cs_channel), &count);
> +
> +	return count;
> +}
> +
> +static u64 notrace ingenic_tcu_timer_cs_read(struct clocksource *cs)
> +{
> +	return ingenic_tcu_timer_read();
> +}
> +
> +static inline struct ingenic_tcu *to_ingenic_tcu(struct 
> clock_event_device *evt)
> +{
> +	return container_of(evt, struct ingenic_tcu, cevt);
> +}
> +
> +static int ingenic_tcu_cevt_set_state_shutdown(struct 
> clock_event_device *evt)
> +{
> +	struct ingenic_tcu *tcu = to_ingenic_tcu(evt);
> +
> +	regmap_write(tcu->map, TCU_REG_TECR, BIT(tcu->timer_channel));
> +
> +	return 0;
> +}
> +
> +static int ingenic_tcu_cevt_set_next(unsigned long next,
> +				     struct clock_event_device *evt)
> +{
> +	struct ingenic_tcu *tcu = to_ingenic_tcu(evt);
> +
> +	if (next > 0xffff)
> +		return -EINVAL;
> +
> +	regmap_write(tcu->map, TCU_REG_TDFRc(tcu->timer_channel), next);
> +	regmap_write(tcu->map, TCU_REG_TCNTc(tcu->timer_channel), 0);
> +	regmap_write(tcu->map, TCU_REG_TESR, BIT(tcu->timer_channel));
> +
> +	return 0;
> +}
> +
> +static irqreturn_t ingenic_tcu_cevt_cb(int irq, void *dev_id)
> +{
> +	struct clock_event_device *evt = dev_id;
> +	struct ingenic_tcu *tcu = to_ingenic_tcu(evt);
> +
> +	regmap_write(tcu->map, TCU_REG_TECR, BIT(tcu->timer_channel));
> +
> +	if (evt->event_handler)
> +		evt->event_handler(evt);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static struct clk * __init ingenic_tcu_get_clock(struct device_node 
> *np, int id)
> +{
> +	struct of_phandle_args args;
> +
> +	args.np = np;
> +	args.args_count = 1;
> +	args.args[0] = id;
> +
> +	return of_clk_get_from_provider(&args);
> +}
> +
> +static int __init ingenic_tcu_timer_init(struct device_node *np,
> +					 struct ingenic_tcu *tcu)
> +{
> +	unsigned int timer_virq, channel = tcu->timer_channel;
> +	struct irq_domain *domain;
> +	unsigned long rate;
> +	int err;
> +
> +	tcu->timer_clk = ingenic_tcu_get_clock(np, channel);
> +	if (IS_ERR(tcu->timer_clk))
> +		return PTR_ERR(tcu->timer_clk);
> +
> +	err = clk_prepare_enable(tcu->timer_clk);
> +	if (err)
> +		goto err_clk_put;
> +
> +	rate = clk_get_rate(tcu->timer_clk);
> +	if (!rate) {
> +		err = -EINVAL;
> +		goto err_clk_disable;
> +	}
> +
> +	domain = irq_find_host(np);
> +	if (!domain) {
> +		err = -ENODEV;
> +		goto err_clk_disable;
> +	}
> +
> +	timer_virq = irq_create_mapping(domain, channel);
> +	if (!timer_virq) {
> +		err = -EINVAL;
> +		goto err_clk_disable;
> +	}
> +
> +	snprintf(tcu->name, sizeof(tcu->name), "TCU");
> +
> +	err = request_irq(timer_virq, ingenic_tcu_cevt_cb, IRQF_TIMER,
> +			  tcu->name, &tcu->cevt);
> +	if (err)
> +		goto err_irq_dispose_mapping;
> +
> +	tcu->cevt.cpumask = cpumask_of(smp_processor_id());
> +	tcu->cevt.features = CLOCK_EVT_FEAT_ONESHOT;
> +	tcu->cevt.name = tcu->name;
> +	tcu->cevt.rating = 200;
> +	tcu->cevt.set_state_shutdown = ingenic_tcu_cevt_set_state_shutdown;
> +	tcu->cevt.set_next_event = ingenic_tcu_cevt_set_next;
> +
> +	clockevents_config_and_register(&tcu->cevt, rate, 10, 0xffff);
> +
> +	return 0;
> +
> +err_irq_dispose_mapping:
> +	irq_dispose_mapping(timer_virq);
> +err_clk_disable:
> +	clk_disable_unprepare(tcu->timer_clk);
> +err_clk_put:
> +	clk_put(tcu->timer_clk);
> +	return err;
> +}
> +
> +static int __init ingenic_tcu_clocksource_init(struct device_node 
> *np,
> +					       struct ingenic_tcu *tcu)
> +{
> +	unsigned int channel = tcu->cs_channel;
> +	struct clocksource *cs = &tcu->cs;
> +	unsigned long rate;
> +	int err;
> +
> +	tcu->cs_clk = ingenic_tcu_get_clock(np, channel);
> +	if (IS_ERR(tcu->cs_clk))
> +		return PTR_ERR(tcu->cs_clk);
> +
> +	err = clk_prepare_enable(tcu->cs_clk);
> +	if (err)
> +		goto err_clk_put;
> +
> +	rate = clk_get_rate(tcu->cs_clk);
> +	if (!rate) {
> +		err = -EINVAL;
> +		goto err_clk_disable;
> +	}
> +
> +	/* Reset channel */
> +	regmap_update_bits(tcu->map, TCU_REG_TCSRc(channel),
> +			   0xffff & ~TCU_TCSR_RESERVED_BITS, 0);
> +
> +	/* Reset counter */
> +	regmap_write(tcu->map, TCU_REG_TDFRc(channel), 0xffff);
> +	regmap_write(tcu->map, TCU_REG_TCNTc(channel), 0);
> +
> +	/* Enable channel */
> +	regmap_write(tcu->map, TCU_REG_TESR, BIT(channel));
> +
> +	cs->name = "ingenic-timer";
> +	cs->rating = 200;
> +	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
> +	cs->mask = CLOCKSOURCE_MASK(16);
> +	cs->read = ingenic_tcu_timer_cs_read;
> +
> +	err = clocksource_register_hz(cs, rate);
> +	if (err)
> +		goto err_clk_disable;
> +
> +	return 0;
> +
> +err_clk_disable:
> +	clk_disable_unprepare(tcu->cs_clk);
> +err_clk_put:
> +	clk_put(tcu->cs_clk);
> +	return err;
> +}
> +
> +static const struct ingenic_soc_info jz4740_soc_info = {
> +	.num_channels = 8,
> +};
> +
> +static const struct ingenic_soc_info jz4725b_soc_info = {
> +	.num_channels = 6,
> +};
> +
> +static const struct of_device_id ingenic_tcu_of_match[] = {
> +	{ .compatible = "ingenic,jz4740-tcu", .data = &jz4740_soc_info, },
> +	{ .compatible = "ingenic,jz4725b-tcu", .data = &jz4725b_soc_info, },
> +	{ .compatible = "ingenic,jz4770-tcu", .data = &jz4740_soc_info, },
> +	{ }
> +};
> +
> +static int __init ingenic_tcu_init(struct device_node *np)
> +{
> +	const struct of_device_id *id = of_match_node(ingenic_tcu_of_match, 
> np);
> +	const struct ingenic_soc_info *soc_info = id->data;
> +	struct ingenic_tcu *tcu;
> +	struct regmap *map;
> +	long rate;
> +	int ret;
> +
> +	of_node_clear_flag(np, OF_POPULATED);
> +
> +	map = ingenic_tcu_get_regmap(np);
> +	if (IS_ERR(map))
> +		return PTR_ERR(map);
> +
> +	tcu = kzalloc(sizeof(*tcu), GFP_KERNEL);
> +	if (!tcu)
> +		return -ENOMEM;
> +
> +	/* Enable all TCU channels for PWM use by default except channels 
> 0/1 */
> +	tcu->pwm_channels_mask = GENMASK(soc_info->num_channels - 1, 2);
> +	of_property_read_u32(np, "ingenic,pwm-channels-mask",
> +			     (u32 *)&tcu->pwm_channels_mask);
> +
> +	/* Verify that we have at least two free channels */
> +	if (hweight8(tcu->pwm_channels_mask) > soc_info->num_channels - 2) {
> +		pr_crit("%s: Invalid PWM channel mask: 0x%02lx\n", __func__,
> +			tcu->pwm_channels_mask);
> +		ret = -EINVAL;
> +		goto err_free_ingenic_tcu;
> +	}
> +
> +	tcu->map = map;
> +	ingenic_tcu = tcu;
> +
> +	tcu->timer_channel = find_first_zero_bit(&tcu->pwm_channels_mask,
> +						 soc_info->num_channels);
> +	tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
> +					     soc_info->num_channels,
> +					     tcu->timer_channel + 1);
> +
> +	ret = ingenic_tcu_clocksource_init(np, tcu);
> +	if (ret) {
> +		pr_crit("%s: Unable to init clocksource: %i\n", __func__, ret);
> +		goto err_free_ingenic_tcu;
> +	}
> +
> +	ret = ingenic_tcu_timer_init(np, tcu);
> +	if (ret)
> +		goto err_tcu_clocksource_cleanup;
> +
> +	/* Register the sched_clock at the end as there's no way to undo it 
> */
> +	rate = clk_get_rate(tcu->cs_clk);
> +	sched_clock_register(ingenic_tcu_timer_read, 16, rate);
> +
> +	return 0;
> +
> +err_tcu_clocksource_cleanup:
> +	clocksource_unregister(&tcu->cs);
> +	clk_disable_unprepare(tcu->cs_clk);
> +	clk_put(tcu->cs_clk);
> +err_free_ingenic_tcu:
> +	kfree(tcu);
> +	return ret;
> +}
> +
> +TIMER_OF_DECLARE(jz4740_tcu_intc,  "ingenic,jz4740-tcu",  
> ingenic_tcu_init);
> +TIMER_OF_DECLARE(jz4725b_tcu_intc, "ingenic,jz4725b-tcu", 
> ingenic_tcu_init);
> +TIMER_OF_DECLARE(jz4770_tcu_intc,  "ingenic,jz4770-tcu",  
> ingenic_tcu_init);
> +
> +
> +static int __init ingenic_tcu_probe(struct platform_device *pdev)
> +{
> +	platform_set_drvdata(pdev, ingenic_tcu);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused ingenic_tcu_suspend(struct device *dev)
> +{
> +	struct ingenic_tcu *tcu = dev_get_drvdata(dev);
> +
> +	clk_disable(tcu->cs_clk);
> +	clk_disable(tcu->timer_clk);
> +	return 0;
> +}
> +
> +static int __maybe_unused ingenic_tcu_resume(struct device *dev)
> +{
> +	struct ingenic_tcu *tcu = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_enable(tcu->timer_clk);
> +	if (ret)
> +		return ret;
> +
> +	ret = clk_enable(tcu->cs_clk);
> +	if (ret) {
> +		clk_disable(tcu->timer_clk);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops __maybe_unused ingenic_tcu_pm_ops = {
> +	/* _noirq: We want the TCU clocks to be gated last / ungated first 
> */
> +	.suspend_noirq = ingenic_tcu_suspend,
> +	.resume_noirq  = ingenic_tcu_resume,
> +};
> +
> +static struct platform_driver ingenic_tcu_driver = {
> +	.driver = {
> +		.name	= "ingenic-tcu-timer",
> +#ifdef CONFIG_PM_SLEEP
> +		.pm	= &ingenic_tcu_pm_ops,
> +#endif
> +		.of_match_table = ingenic_tcu_of_match,
> +	},
> +};
> +builtin_platform_driver_probe(ingenic_tcu_driver, ingenic_tcu_probe);
> --
> 2.21.0.593.g511ec345e18
>