Re: [PATCH v8 2/2] clocksource: Add Intel Keem Bay timer support

Daniel Lezcano
2022-03-01T21:09:17Z

On 22/02/2022 10:56, shruthi.sanil@intel.com wrote:
> From: Shruthi Sanil <shruthi.sanil@intel.com>
>
> The Intel Keem Bay timer driver supports clocksource and clockevent
> features for the timer IP used in Intel Keem Bay SoC.
> The timer block supports 1 free running counter and 8 timers.
> The free running counter can be used as a clocksource and
> the timers can be used as clockevent. Each timer is capable of
> generating individual interrupt.
> Both the features are enabled through the timer general config register.
>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
> Signed-off-by: Shruthi Sanil <shruthi.sanil@intel.com>
> ---
> MAINTAINERS | 6 +
> drivers/clocksource/Kconfig | 11 ++
> drivers/clocksource/Makefile | 1 +
> drivers/clocksource/timer-keembay.c | 230 ++++++++++++++++++++++++++++
> 4 files changed, 248 insertions(+)
> create mode 100644 drivers/clocksource/timer-keembay.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 777cd6fa2b3d..73c0029dcdf7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9796,6 +9796,12 @@ F: drivers/crypto/keembay/keembay-ocs-hcu-core.c
> F: drivers/crypto/keembay/ocs-hcu.c
> F: drivers/crypto/keembay/ocs-hcu.h
>
> +INTEL KEEM BAY TIMER DRIVER
> +M: Shruthi Sanil <shruthi.sanil@intel.com>
> +S: Maintained
> +F: Documentation/devicetree/bindings/timer/intel,keembay-timer.yaml
> +F: drivers/clocksource/timer-keembay.c
> +
> INTEL THUNDER BAY EMMC PHY DRIVER
> M: Nandhini Srikandan <nandhini.srikandan@intel.com>
> M: Rashmi A <rashmi.a@intel.com>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index cfb8ea0df3b1..65b6cf916e5a 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -721,4 +721,15 @@ config MICROCHIP_PIT64B
> modes and high resolution. It is used as a clocksource
> and a clockevent.
>
> +config KEEMBAY_TIMER
> + bool "Intel Keem Bay timer"
> + depends on ARCH_KEEMBAY || COMPILE_TEST
> + select TIMER_OF
> + help
> + This option enables the support for the Intel Keem Bay
> + general purpose timer and free running counter driver.
> + Each timer can generate an individual interrupt and
> + supports oneshot and periodic modes.
> + The 64-bit counter can be used as a clock source.
> +
> endmenu
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index fa5f624eadb6..dff6458ef9e5 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -89,3 +89,4 @@ obj-$(CONFIG_GX6605S_TIMER) += timer-gx6605s.o
> obj-$(CONFIG_HYPERV_TIMER) += hyperv_timer.o
> obj-$(CONFIG_MICROCHIP_PIT64B) += timer-microchip-pit64b.o
> obj-$(CONFIG_MSC313E_TIMER) += timer-msc313e.o
> +obj-$(CONFIG_KEEMBAY_TIMER) += timer-keembay.o
> diff --git a/drivers/clocksource/timer-keembay.c b/drivers/clocksource/timer-keembay.c
> new file mode 100644
> index 000000000000..230609c06a26
> --- /dev/null
> +++ b/drivers/clocksource/timer-keembay.c
> @@ -0,0 +1,230 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Intel Keem Bay Timer driver
> + *
> + * Copyright (C) 2020 Intel Corporation
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/interrupt.h>
> +#include <linux/io-64-nonatomic-lo-hi.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/sizes.h>
> +#include <linux/slab.h>
> +#include <linux/regmap.h>
> +
> +#include "timer-of.h"
> +
> +/* Timer register offset */
> +#define TIM_CNT_VAL_OFFSET 0x0
> +#define TIM_RELOAD_VAL_OFFSET 0x4
> +#define TIM_CONFIG_OFFSET 0x8
> +
> +/* Bit fields of timer general config register */
> +#define TIM_CONFIG_PRESCALER_ENABLE BIT(2)
> +#define TIM_CONFIG_COUNTER_ENABLE BIT(0)
> +
> +/* Bit fields of timer config register */
> +#define TIM_CONFIG_INTERRUPT_PENDING BIT(4)
> +#define TIM_CONFIG_INTERRUPT_ENABLE BIT(2)
> +#define TIM_CONFIG_RESTART BIT(1)
> +#define TIM_CONFIG_ENABLE BIT(0)
> +
> +#define TIM_GEN_MASK GENMASK(31, 12)
> +#define TIM_RATING 200
> +#define TIM_CLKSRC_MASK_BITS 64
> +
> +#define TIMER_NAME_SIZE 25
> +
> +static inline void keembay_timer_enable(void __iomem *base, u32 flags)
> +{
> + writel(TIM_CONFIG_ENABLE | flags, base + TIM_CONFIG_OFFSET);
> +}
> +
> +static inline void keembay_timer_disable(void __iomem *base)
> +{
> + writel(0x0, base + TIM_CONFIG_OFFSET);
> +}
> +
> +static inline void keembay_timer_update_counter(void __iomem *base, u32 val)
> +{
> + writel(val, base + TIM_CNT_VAL_OFFSET);
> + writel(val, base + TIM_RELOAD_VAL_OFFSET);
> +}
> +
> +static inline void keembay_timer_clear_pending_int(void __iomem *base)
> +{
> + u32 val;
> +
> + val = readl(base + TIM_CONFIG_OFFSET);
> + val &= ~TIM_CONFIG_INTERRUPT_PENDING;
> + writel(val, base + TIM_CONFIG_OFFSET);
> +}
> +
> +static int keembay_timer_set_next_event(unsigned long evt, struct clock_event_device *ce)
> +{
> + u32 flags = TIM_CONFIG_INTERRUPT_ENABLE;
> + struct timer_of *to = to_timer_of(ce);
> + void __iomem *tim_base = timer_of_base(to);
> +
> + keembay_timer_disable(tim_base);
> + keembay_timer_update_counter(tim_base, evt);
> + keembay_timer_enable(tim_base, flags);
> +
> + return 0;
> +}
> +
> +static int keembay_timer_periodic(struct clock_event_device *ce)
> +{
> + u32 flags = TIM_CONFIG_INTERRUPT_ENABLE | TIM_CONFIG_RESTART;
> + struct timer_of *to = to_timer_of(ce);
> + void __iomem *tim_base = timer_of_base(to);
> +
> + keembay_timer_disable(tim_base);
> + keembay_timer_update_counter(tim_base, timer_of_period(to));
> + keembay_timer_enable(tim_base, flags);
> +
> + return 0;
> +}
> +
> +static int keembay_timer_shutdown(struct clock_event_device *ce)
> +{
> + struct timer_of *to = to_timer_of(ce);
> +
> + keembay_timer_disable(timer_of_base(to));
> +
> + return 0;
> +}
> +
> +static irqreturn_t keembay_timer_isr(int irq, void *dev_id)
> +{
> + struct clock_event_device *evt = dev_id;
> + struct timer_of *to = to_timer_of(evt);
> + void __iomem *tim_base = timer_of_base(to);
> + u32 val;
> +
> + val = readl(tim_base + TIM_CONFIG_OFFSET);
> +
> + if (val & TIM_CONFIG_RESTART) {
> + /* Clear interrupt for periodic timer*/

nit: comment format is:

/*
* my comment
*/

One line comment format is usually for the network subsystem

> + keembay_timer_clear_pending_int(tim_base);
> + } else {
> + /* Disable the timer for one shot timer */

comment format

> + keembay_timer_disable(tim_base);
> + }
> +
> + evt->event_handler(evt);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int __init keembay_clockevent_init(struct device_node *np)
> +{
> + struct timer_of *keembay_ce_to;
> + struct regmap *regmap;
> + int ret;
> + u32 val;
> +
> + regmap = device_node_to_regmap(np->parent);
> + if (IS_ERR(regmap))
> + return PTR_ERR(regmap);
> +
> + ret = regmap_read(regmap, TIM_CONFIG_OFFSET, &val);
> + if (ret)
> + return ret;
> +
> + /* Prescaler bit must be enabled for the timer to function */

comment format

> + if (!(val & TIM_CONFIG_PRESCALER_ENABLE)) {
> + pr_err("%pOF: Prescaler is not enabled\n", np);
> + ret = -ENODEV;
> + }

Why bail out instead of enabling the prescalar ?

> + keembay_ce_to = kzalloc(sizeof(*keembay_ce_to), GFP_KERNEL);
> + if (!keembay_ce_to)
> + ret = -ENOMEM;

As your convenience but I suggest global static variable initialization,
that will simplify the init function regarding the error path.

> + keembay_ce_to->flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK;
> + keembay_ce_to->clkevt.name = "keembay_timer";
> + keembay_ce_to->clkevt.cpumask = cpu_possible_mask;
> + keembay_ce_to->clkevt.features = CLOCK_EVT_FEAT_PERIODIC |
> + CLOCK_EVT_FEAT_ONESHOT |
> + CLOCK_EVT_FEAT_DYNIRQ;
> + keembay_ce_to->clkevt.rating = TIM_RATING;
> + keembay_ce_to->clkevt.set_next_event = keembay_timer_set_next_event;
> + keembay_ce_to->clkevt.set_state_periodic = keembay_timer_periodic;
> + keembay_ce_to->clkevt.set_state_shutdown = keembay_timer_shutdown;
> + keembay_ce_to->of_irq.handler = keembay_timer_isr;
> + keembay_ce_to->of_irq.flags = IRQF_TIMER;
> +
> + ret = timer_of_init(np, keembay_ce_to);
> + if (ret)
> + goto err_keembay_ce_to_free;
> +
> + ret = regmap_read(regmap, TIM_RELOAD_VAL_OFFSET, &val);
> + if (ret)
> + goto err_keembay_ce_to_free;
> +
> + keembay_ce_to->of_clk.rate = keembay_ce_to->of_clk.rate / (val + 1);
> +
> + clockevents_config_and_register(&keembay_ce_to->clkevt,
> + timer_of_rate(keembay_ce_to),
> + 1,
> + U32_MAX);
> +
> + return 0;
> +
> +err_keembay_ce_to_free:
> + kfree(keembay_ce_to);
> +
> + return ret;
> +}
> +
> +static struct timer_of keembay_cs_to = {
> + .flags = TIMER_OF_BASE | TIMER_OF_CLOCK,
> +};
> +
> +static u64 notrace keembay_clocksource_read(struct clocksource *cs)
> +{
> + return lo_hi_readq(timer_of_base(&keembay_cs_to));
> +}
> +
> +static struct clocksource keembay_counter = {
> + .name = "keembay_sys_counter",
> + .rating = TIM_RATING,
> + .read = keembay_clocksource_read,
> + .mask = CLOCKSOURCE_MASK(TIM_CLKSRC_MASK_BITS),
> + .flags = CLOCK_SOURCE_IS_CONTINUOUS |
> + CLOCK_SOURCE_SUSPEND_NONSTOP,
> +};
> +
> +static int __init keembay_clocksource_init(struct device_node *np)
> +{
> + struct regmap *regmap;
> + u32 val;
> + int ret;
> +
> + regmap = device_node_to_regmap(np->parent);
> + if (IS_ERR(regmap))
> + return PTR_ERR(regmap);
> +
> + ret = regmap_read(regmap, TIM_CONFIG_OFFSET, &val);
> + if (ret)
> + return ret;
> +
> + /* Free Running Counter bit must be enabled for counter to function */

comment format

> + if (!(val & TIM_CONFIG_COUNTER_ENABLE)) {
> + pr_err("%pOF: free running counter is not enabled\n", np);
> + return -ENODEV;
> + }

Same comment as above. Why not enable the counter ?

Other than that, the driver is having a good shape

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