Re: [PATCH v5 1/6] clocksource: Add support for the Mediatek SoCs

Daniel Lezcano
2014-05-23T17:39:16Z

On 05/21/2014 06:26 PM, Matthias Brugger wrote:
> This patch adds a clock source and clock event for the timer found
> on the Mediatek SoCs.
>
> The Mediatek General Porpose Timer block provides five 32 bit timers and

s/Porpose/Purpose

> one 64 bit timer.
>
> Two 32 bit timers are used:
> TIMER1: clock events supporting periodic and oneshot events
> TIMER2: clock source configured as a free running counter
>
> The General Porpose Timer block can be run with two clocks. A 13 MHz system

s/Porpose/Purpose

> clock and the RTC clock running at 32 KHz. This implementation uses the system
> clock.

As it is a new driver, could you elaborate a bit the description of this
driver please ? Behavior, some oddities, etc ...

> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
> ---
> drivers/clocksource/Kconfig | 4 +
> drivers/clocksource/Makefile | 1 +
> drivers/clocksource/mtk_timer.c | 263 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 268 insertions(+)
> create mode 100644 drivers/clocksource/mtk_timer.c
>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 96918e1..1f73740 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -144,6 +144,10 @@ config VF_PIT_TIMER
> config SYS_SUPPORTS_SH_CMT
> bool
>
> +config MTK_TIMER
> + select CLKSRC_MMIO
> + bool
> +
> config SYS_SUPPORTS_SH_MTU2
> bool
>
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 98cb6c5..619d302 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -33,6 +33,7 @@ obj-$(CONFIG_CLKSRC_EXYNOS_MCT) += exynos_mct.o
> obj-$(CONFIG_CLKSRC_SAMSUNG_PWM) += samsung_pwm_timer.o
> obj-$(CONFIG_VF_PIT_TIMER) += vf_pit_timer.o
> obj-$(CONFIG_CLKSRC_QCOM) += qcom-timer.o
> +obj-$(CONFIG_MTK_TIMER) += mtk_timer.o
>
> obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
> obj-$(CONFIG_ARM_GLOBAL_TIMER) += arm_global_timer.o
> diff --git a/drivers/clocksource/mtk_timer.c b/drivers/clocksource/mtk_timer.c
> new file mode 100644
> index 0000000..f86b5080
> --- /dev/null
> +++ b/drivers/clocksource/mtk_timer.c
> @@ -0,0 +1,263 @@
> +/*
> + * Mediatek SoCs General-Purpose Timer handling.
> + *
> + * Copyright (C) 2014 Matthias Brugger
> + *
> + * Matthias Brugger <matthias.bgg@gmail.com>
> + *
> + * 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; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clockchips.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqreturn.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/slab.h>
> +
> +#define GPT_IRQ_EN_REG 0x00
> +#define GPT_IRQ_ENABLE(val) BIT(val-1)
> +#define GPT_IRQ_ST_REG 0x04
> +#define GPT_IRQ_ACK_REG 0x08
> +#define GPT_IRQ_ACK(val) BIT(val-1)
> +
> +#define TIMER_CTRL_REG(val) (0x10 * val)
> +#define TIMER_CTRL_OP(val) (((val) & 0x3) << 4)
> +#define TIMER_CTRL_OP_ONESHOT (0)
> +#define TIMER_CTRL_OP_REPEAT (1)
> +#define TIMER_CTRL_OP_KEEPGO (2)
> +#define TIMER_CTRL_OP_FREERUN (3)
> +#define TIMER_CTRL_CLEAR (2)
> +#define TIMER_CTRL_ENABLE (1)
> +#define TIMER_CTRL_DISABLE (0)
> +
> +#define TIMER_CLK_REG(val) (0x04 + (0x10 * val))
> +#define TIMER_CLK_SRC(val) (((val) & 0x1) << 4)
> +#define TIMER_CLK_SRC_SYS13M (0)
> +#define TIMER_CLK_SRC_RTC32K (1)
> +#define TIMER_CLK_DIV1 (0x0)
> +#define TIMER_CLK_DIV2 (0x1)
> +#define TIMER_CLK_DIV3 (0x2)
> +#define TIMER_CLK_DIV4 (0x3)
> +#define TIMER_CLK_DIV5 (0x4)
> +#define TIMER_CLK_DIV6 (0x5)
> +#define TIMER_CLK_DIV7 (0x6)
> +#define TIMER_CLK_DIV8 (0x7)
> +#define TIMER_CLK_DIV9 (0x8)
> +#define TIMER_CLK_DIV10 (0x9)
> +#define TIMER_CLK_DIV11 (0xA)
> +#define TIMER_CLK_DIV12 (0xB)
> +#define TIMER_CLK_DIV13 (0xC)
> +#define TIMER_CLK_DIV16 (0xD)
> +#define TIMER_CLK_DIV32 (0xE)
> +#define TIMER_CLK_DIV64 (0xF)
> +
> +#define TIMER_CNT_REG(val) (0x08 + (0x10 * val))
> +#define TIMER_CMP_REG(val) (0x0C + (0x10 * val))

Please remove unused macros.

> +
> +#define GPT_CLK_EVT 1
> +#define GPT_CLK_SRC 2
> +
> +
> +

extra lines.

> +struct mtk_clock_event_device {
> + void __iomem *gpt_base;
> + u32 ticks_per_jiffy;
> + struct clock_event_device dev;
> +};
> +
> +static inline struct mtk_clock_event_device *to_mtk_clk(
> + struct clock_event_device *c)
> +{
> + return container_of(c, struct mtk_clock_event_device, dev);
> +}
> +
> +static void mtk_clkevt_time_stop(struct mtk_clock_event_device *evt, u8 timer)
> +{
> + u32 val = readl(evt->gpt_base + TIMER_CTRL_REG(timer));
> + writel(val & ~TIMER_CTRL_ENABLE, evt->gpt_base +
> + TIMER_CTRL_REG(timer));
> +}
> +
> +static void mtk_clkevt_time_setup(struct mtk_clock_event_device *evt,
> + unsigned long delay, u8 timer)
> +{
> + writel(delay, evt->gpt_base + TIMER_CMP_REG(timer));
> +}
> +
> +static void mtk_clkevt_time_start(struct mtk_clock_event_device *evt,
> + bool periodic, u8 timer)
> +{
> + u32 val;
> +
> + /* Acknowledge interrupt */
> + writel(GPT_IRQ_ACK(timer), evt->gpt_base + GPT_IRQ_ACK_REG);
> +
> + val = readl(evt->gpt_base + TIMER_CTRL_REG(timer));
> +
> + /* Clear 2 bit timer operation mode field */
> + val &= ~TIMER_CTRL_OP(0x3);
> +
> + if (periodic)
> + val |= TIMER_CTRL_OP(TIMER_CTRL_OP_REPEAT);
> + else
> + val |= TIMER_CTRL_OP(TIMER_CTRL_OP_ONESHOT);
> +
> + writel(val | TIMER_CTRL_ENABLE | TIMER_CTRL_CLEAR,
> + evt->gpt_base + TIMER_CTRL_REG(timer));
> +}
> +
> +static void mtk_clkevt_mode(enum clock_event_mode mode,
> + struct clock_event_device *clk)
> +{
> + struct mtk_clock_event_device *evt = to_mtk_clk(clk);
> +
> + mtk_clkevt_time_stop(evt, GPT_CLK_EVT);
> +
> + switch (mode) {
> + case CLOCK_EVT_MODE_PERIODIC:
> + mtk_clkevt_time_setup(evt, evt->ticks_per_jiffy, GPT_CLK_EVT);
> + mtk_clkevt_time_start(evt, true, GPT_CLK_EVT);
> + break;
> + case CLOCK_EVT_MODE_ONESHOT:
> + mtk_clkevt_time_start(evt, false, GPT_CLK_EVT);
> + break;
> + case CLOCK_EVT_MODE_UNUSED:
> + case CLOCK_EVT_MODE_SHUTDOWN:
> + default:
> + /* No more interrupts will occur as source is disabled */
> + break;
> + }
> +}
> +
> +static int mtk_clkevt_next_event(unsigned long event,
> + struct clock_event_device *clk)
> +{
> + struct mtk_clock_event_device *evt = to_mtk_clk(clk);
> +
> + mtk_clkevt_time_stop(evt, GPT_CLK_EVT);
> + mtk_clkevt_time_setup(evt, event, GPT_CLK_EVT);
> + mtk_clkevt_time_start(evt, false, GPT_CLK_EVT);
> +
> + return 0;
> +}
> +
> +static irqreturn_t mtk_timer_interrupt(int irq, void *dev_id)
> +{
> + struct mtk_clock_event_device *evt = dev_id;
> +
> + /* Acknowledge timer0 irq */
> + writel(GPT_IRQ_ACK(GPT_CLK_EVT), evt->gpt_base + GPT_IRQ_ACK_REG);
> + evt->dev.event_handler(&evt->dev);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static void mtk_timer_global_reset(struct mtk_clock_event_device *evt)
> +{
> + /* Disable all interrupts */
> + writel(0x0, evt->gpt_base + GPT_IRQ_EN_REG);
> + /* Acknowledge all interrupts */
> + writel(0x3f, evt->gpt_base + GPT_IRQ_ACK_REG);
> +}
> +
> +static void mtk_timer_reset(struct mtk_clock_event_device *evt, u8 timer)
> +{
> + writel(TIMER_CTRL_CLEAR | TIMER_CTRL_DISABLE,
> + evt->gpt_base + TIMER_CTRL_REG(timer));
> + writel(0x0, evt->gpt_base + TIMER_CMP_REG(timer));
> +}
> +
> +static void __init mtk_timer_init(struct device_node *node)
> +{
> + struct mtk_clock_event_device *evt;
> + struct resource res;
> + unsigned long rate = 0;
> + struct clk *clk;
> + int ret;
> + u32 val;
> +
> + evt = kzalloc(sizeof(*evt), GFP_KERNEL);
> + if (!evt)
> + panic("Can't allocate mtk clock event driver struct");
> +
> + evt->dev.name = "mtk_tick";
> + evt->dev.rating = 300;
> + evt->dev.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
> + evt->dev.set_mode = mtk_clkevt_mode;
> + evt->dev.set_next_event = mtk_clkevt_next_event;
> + evt->dev.cpumask = cpu_possible_mask;
> +
> + if (of_address_to_resource(node, 0, &res))
> + panic("Failed to parse resource\n");
> +
> + if (!request_mem_region(res.start, resource_size(&res), "mtk-timer"))
> + panic("Registers are a busy IO resource");
> +
> + evt->gpt_base = ioremap(res.start, resource_size(&res));
> + if (!evt->gpt_base)
> + panic("Can't map registers");
> +
> + evt->dev.irq = irq_of_parse_and_map(node, 0);
> + if (evt->dev.irq <= 0)
> + panic("Can't parse IRQ");
> +
> + clk = of_clk_get(node, 0);
> + if (IS_ERR(clk))
> + panic("Can't get timer clock");
> +
> + clk_prepare_enable(clk);
> + rate = clk_get_rate(clk);
> +
> + mtk_timer_global_reset(evt);
> +
> + /* Configure clock source */
> + mtk_timer_reset(evt, GPT_CLK_SRC);
> +
> + writel(TIMER_CLK_SRC(TIMER_CLK_SRC_SYS13M) | TIMER_CLK_DIV1,
> + evt->gpt_base + TIMER_CLK_REG(GPT_CLK_SRC));
> +
> + writel(TIMER_CTRL_OP(TIMER_CTRL_OP_FREERUN) | TIMER_CTRL_ENABLE,
> + evt->gpt_base + TIMER_CTRL_REG(GPT_CLK_SRC));
> +
> + clocksource_mmio_init(evt->gpt_base + TIMER_CNT_REG(GPT_CLK_SRC),
> + node->name, rate, 300, 32, clocksource_mmio_readl_up);
> +
> + evt->ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
> +
> + /* Configure clock event */
> + mtk_timer_reset(evt, GPT_CLK_EVT);
> +
> + writel(TIMER_CLK_SRC(TIMER_CLK_SRC_SYS13M) | TIMER_CLK_DIV1,
> + evt->gpt_base + TIMER_CLK_REG(GPT_CLK_EVT));
> + writel(0, evt->gpt_base + TIMER_CMP_REG(GPT_CLK_EVT));
> +
> + writel(TIMER_CTRL_OP(TIMER_CTRL_OP_REPEAT) | TIMER_CTRL_ENABLE,
> + evt->gpt_base + TIMER_CTRL_REG(GPT_CLK_EVT));
> +
> + ret = request_irq(evt->dev.irq, mtk_timer_interrupt,
> + IRQF_TIMER | IRQF_IRQPOLL, "mtk_timer", evt);
> + if (ret)
> + pr_warn("failed to setup irq %d\n", evt->dev.irq);
> +
> + /* Enable timer0 interrupt */
> + val = readl(evt->gpt_base + GPT_IRQ_EN_REG);
> + writel(val | GPT_IRQ_ENABLE(GPT_CLK_EVT),
> + evt->gpt_base + GPT_IRQ_EN_REG);

Could you encapsulate in well named functions the different 'writel' above ?

> + clockevents_config_and_register(&evt->dev, rate, 0x3,
> + 0xffffffff);
> +}
> +CLOCKSOURCE_OF_DECLARE(mtk_mt6589, "mediatek,mtk6577-timer", mtk_timer_init);
> +
>

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