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

From: Daniel Lezcano
Date: Fri May 23 2014 - 13:39:20 EST

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@xxxxxxxxx>
---
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@xxxxxxxxx>
+ *
+ * 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);
+



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

Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/