Re: [PATCH v1 1/2] clocksource: npcm: add NPCM7xx timer driver

Daniel Lezcano
2017-10-01T16:45:09Z

Hi Tomer,

On Sun, Oct 01, 2017 at 12:11:37PM +0300, Tomer Maimon wrote:
> Add Nuvoton BMC NPCM7xx timer driver.

Give a more detailed description of the timer please.

> Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>
> ---
> drivers/clocksource/Kconfig | 9 ++
> drivers/clocksource/Makefile | 1 +
> drivers/clocksource/npcm7xx_timer.c | 205 ++++++++++++++++++++++++++++++++++++

Rename the driver to timer-npcm7xx.c

> 3 files changed, 215 insertions(+)
> create mode 100644 drivers/clocksource/npcm7xx_timer.c
>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index cc6062049170..e26a203ce4ab 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -140,6 +140,15 @@ config VT8500_TIMER
> help
> Enables support for the VT8500 driver.
>
> +config NPCM7XX_TIMER
> + bool "NPCM7xx timer driver" if (COMPILE_TEST || ARCH_NPCM7XX)

Remove the ARCH_NPCM7XX dependency, we want to have the timer selection hidden.

> + depends on GENERIC_CLOCKEVENTS

You can remove this dependency, there is a patch in the queue moving the
dependency up for all the timers.

> + depends on HAS_IOMEM
> + select CLKSRC_MMIO
> + help
> + Enable 24-bit TIMER0 and TIMER1 counters in the NPCM7xx arcithcture,
> + While TIMER0 serves as clockevent and TIMER1 serves as clocksource.
> +
> config CADENCE_TTC_TIMER
> bool "Cadence TTC timer driver" if COMPILE_TEST
> depends on COMMON_CLK
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index dbc1ad14515e..fd3a1c33364b 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -53,6 +53,7 @@ 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-$(CONFIG_NPCM7XX_TIMER) += npcm7xx_timer.o
>
> obj-$(CONFIG_ARC_TIMERS) += arc_timer.o
> obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
> diff --git a/drivers/clocksource/npcm7xx_timer.c b/drivers/clocksource/npcm7xx_timer.c
> new file mode 100644
> index 000000000000..6da77202a22d
> --- /dev/null
> +++ b/drivers/clocksource/npcm7xx_timer.c
> @@ -0,0 +1,205 @@
> +/*
> + * Copyright (c) 2017 Nuvoton Technology corporation.
> + * Copyright 2017 Google, Inc.
> + *
> + * 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;version 2 of the License.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/sched.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/err.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +#include <linux/clockchips.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_address.h>
> +
> +struct npcm7xx_clockevent_data {
> + struct clock_event_device cvd;
> + void __iomem *timer_base;
> + unsigned int rate;
> +};
> +
> +/* Timers registers */
> +#define REG_TCSR0 0x0 /* Timer 0 Control and Status Register */
> +#define REG_TICR0 0x8 /* Timer 0 Initial Count Register */
> +#define REG_TCSR1 0x4 /* Timer 1 Control and Status Register */
> +#define REG_TICR1 0xc /* Timer 1 Initial Count Register */
> +#define REG_TDR1 0x14 /* Timer 1 Data Register */
> +#define REG_TISR 0x18 /* Timer Interrupt Status Register */
> +
> +#define RESETINT 0x1f
> +#define PERIOD BIT(27)
> +#define INTEN BIT(29)
> +#define COUNTEN BIT(30)
> +#define ONESHOT 0x0
> +#define TIMER_OPER GENMASK(3, 27)
> +#define MIN_PRESCALE 0x1 /* minimal timer prescale */
> +#define TDR_MASK_BITS 24

Extra tab.

The macro names are too generic, please prefix them, eg. NPCM7XX_PERIOD

> +#define MAX_TIMER_CNT 0xFFFFFF
> +#define CLR_TIMER0_INT 0x1
> +#define CLR_TIMER_CSR 0x0
>
> +static int npcm7xx_timer_oneshot(struct clock_event_device *evt)
> +{
> + u32 val;
> + struct npcm7xx_clockevent_data *cevtd =
> + container_of(evt, struct npcm7xx_clockevent_data, cvd);

nit: alignment

> +
> + val = readl(cevtd->timer_base + REG_TCSR0);
> + val &= ~TIMER_OPER;
> +
> + val = readl(cevtd->timer_base + REG_TCSR0);
> + val |= (ONESHOT | COUNTEN | INTEN | MIN_PRESCALE);

These flags combination may deserve a macro.

> + writel(val, cevtd->timer_base + REG_TCSR0);
> +
> + return 0;
> +}
> +
> +static int npcm7xx_timer_periodic(struct clock_event_device *evt)
> +{
> + struct npcm7xx_clockevent_data *cevtd =
> + container_of(evt, struct npcm7xx_clockevent_data, cvd);
> + u32 val;
> +
> + val = readl(cevtd->timer_base + REG_TCSR0);
> + val &= ~TIMER_OPER;
> +
> + writel((cevtd->rate / HZ), cevtd->timer_base + REG_TICR0);
> + val |= (PERIOD | COUNTEN | INTEN | MIN_PRESCALE);
> +
> + writel(val, cevtd->timer_base + REG_TCSR0);
> +
> + return 0;
> +}
> +
> +static int npcm7xx_clockevent_setnextevent(unsigned long evt,
> + struct clock_event_device *clk)
> +{
> + struct npcm7xx_clockevent_data *cevtd =
> + container_of(clk, struct npcm7xx_clockevent_data, cvd);
> + u32 val;
> +
> + writel(evt, cevtd->timer_base + REG_TICR0);
> + val = readl(cevtd->timer_base + REG_TCSR0);
> + val |= (COUNTEN | INTEN | MIN_PRESCALE);
> + writel(val, cevtd->timer_base + REG_TCSR0);
> +
> + return 0;
> +}
> +
> +static struct npcm7xx_clockevent_data npcm7xx_clockevent_data = {
> + .cvd = {
> + .name = "npcm7xx-timer0",
> + .features = CLOCK_EVT_FEAT_PERIODIC |
> + CLOCK_EVT_FEAT_ONESHOT,
> + .set_next_event = npcm7xx_clockevent_setnextevent,
> + .set_state_shutdown = npcm7xx_timer_oneshot,
> + .set_state_periodic = npcm7xx_timer_periodic,
> + .set_state_oneshot = npcm7xx_timer_oneshot,
> + .tick_resume = npcm7xx_timer_oneshot,
> + .rating = 300
> + },
> +};
> +
> +static irqreturn_t npcm7xx_timer0_interrupt(int irq, void *dev_id)
> +{
> + struct npcm7xx_clockevent_data *cevtd = dev_id;
> + struct clock_event_device *evt = &cevtd->cvd;
> +
> + writel(CLR_TIMER0_INT, cevtd->timer_base + REG_TISR);
> +
> + if (evt->event_handler)
> + evt->event_handler(evt);

In which scenario it is possible to have this condition false?

> + return IRQ_HANDLED;
> +}
> +
> +static struct irqaction npcm7xx_timer0_irq = {
> + .name = "npcm7xx-timer0",
> + .flags = IRQF_TIMER | IRQF_IRQPOLL,
> + .handler = npcm7xx_timer0_interrupt,
> + .dev_id = &npcm7xx_clockevent_data,
> +};
> +
> +static void __init npcm7xx_clockevents_init(int irq, u32 rate)
> +{
> + writel(CLR_TIMER_CSR, npcm7xx_clockevent_data.timer_base + REG_TCSR0);
> +
> + writel(RESETINT, npcm7xx_clockevent_data.timer_base + REG_TISR);
> + setup_irq(irq, &npcm7xx_timer0_irq);

Consider using request_irq instead of setup_irq or, see below, timer-of.c API.

> + npcm7xx_clockevent_data.cvd.cpumask = cpumask_of(0);
> +
> + clockevents_config_and_register(&npcm7xx_clockevent_data.cvd, rate,
> + 0x1, MAX_TIMER_CNT);
> +}
> +
> +static void __init npcm7xx_clocksource_init(u32 rate)
> +{
> + u32 val;
> +
> + writel(CLR_TIMER_CSR, npcm7xx_clockevent_data.timer_base + REG_TCSR1);
> + writel(MAX_TIMER_CNT, npcm7xx_clockevent_data.timer_base + REG_TICR1);
> +
> + val = readl(npcm7xx_clockevent_data.timer_base + REG_TCSR1);
> + val |= (COUNTEN | PERIOD | MIN_PRESCALE);
> + writel(val, npcm7xx_clockevent_data.timer_base + REG_TCSR1);
> +
> + clocksource_mmio_init(npcm7xx_clockevent_data.timer_base + REG_TDR1,
> + "npcm7xx-timer1", rate,
> + 300, (unsigned int)TDR_MASK_BITS,
> + clocksource_mmio_readl_down);
> +}
> +
> +static int __init npcm7xx_timer_init(struct device_node *np)
> +{
> + struct clk *clk;
> + int irq, ret;
> + u32 rate;
> +
> + irq = irq_of_parse_and_map(np, 0);
> + if (!irq)
> + return -EINVAL;
> +
> + npcm7xx_clockevent_data.timer_base = of_iomap(np, 0);
> + if (!npcm7xx_clockevent_data.timer_base)
> + return -ENXIO;
> +
> + clk = of_clk_get(np, 0);
> +
> + if (IS_ERR(clk)) {
> + ret = of_property_read_u32(np, "clock-frequency", &rate);
> + if (ret)
> + goto err_iounmap;
> + } else {
> + clk_prepare_enable(clk);
> + rate = clk_get_rate(clk);
> + }
> +
> + /* Clock input is divided by PRESCALE + 1 before it is fed */
> + /* to the counter */
> + rate = rate / (MIN_PRESCALE + 1);
> +
> + npcm7xx_clockevent_data.rate = rate;

Can you consider using the timer-of.c API? It should simplify the code.

> +
> + npcm7xx_clocksource_init(rate);
> + npcm7xx_clockevents_init(irq, rate);
> +
> + pr_info("Enabling NPCM7xx clocksource timer base: %p, IRQ: %u\n",
> + npcm7xx_clockevent_data.timer_base, irq);
> +
> + return 0;
> +
> +err_iounmap:
> + iounmap(npcm7xx_clockevent_data.timer_base);
> + return ret;
> +
> +}
> +
> +TIMER_OF_DECLARE(npcm7xx, "nuvoton,npcm7xx-timer", npcm7xx_timer_init);
> +
> --
> 2.14.1
>

--

<http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |