[PATCH v3 1/2] clocksource: Add Oxford Semiconductor RPS Dual Timer

Neil Armstrong
2016-06-15T10:14:04Z

Add clocksource and clockevent driver from dual RPS timer.
The HW provides a dual one-shot or periodic 24bit timers,
the drivers set the first one as tick event source and the
second as a continuous scheduler clock source.
The timer can use 1, 16 or 256 as pre-dividers, thus the
clocksource uses 16 by default.

CC: Ma Haijun <mahaijuns@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
drivers/clocksource/Kconfig | 7 +
drivers/clocksource/Makefile | 1 +
drivers/clocksource/timer-oxnas-rps.c | 290 ++++++++++++++++++++++++++++++++++
3 files changed, 298 insertions(+)
create mode 100644 drivers/clocksource/timer-oxnas-rps.c

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 47352d2..7e937e1 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -293,6 +293,13 @@ config VF_PIT_TIMER
help
Support for Period Interrupt Timer on Freescale Vybrid Family SoCs.

+config OXNAS_RPS_TIMER
+ bool "Oxford Semiconductor OXNAS RPS Timers driver" if COMPILE_TEST
+ select CLKSRC_OF
+ select CLKSRC_MMIO
+ help
+ This enables support for the Oxford Semiconductor OXNAS RPS timers.
+
config SYS_SUPPORTS_SH_CMT
bool

diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 473974f..bc66981 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_MTK_TIMER) += mtk_timer.o
obj-$(CONFIG_CLKSRC_PISTACHIO) += time-pistachio.o
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-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
obj-$(CONFIG_ARM_GLOBAL_TIMER) += arm_global_timer.o
diff --git a/drivers/clocksource/timer-oxnas-rps.c b/drivers/clocksource/timer-oxnas-rps.c
new file mode 100644
index 0000000..c002e99
--- /dev/null
+++ b/drivers/clocksource/timer-oxnas-rps.c
@@ -0,0 +1,290 @@
+/*
+ * drivers/clocksource/timer-oxnas-rps.c
+ *
+ * Copyright (C) 2009 Oxford Semiconductor Ltd
+ * Copyright (C) 2013 Ma Haijun <mahaijuns@gmail.com>
+ * Copyright (C) 2016 Neil Armstrong <narmstrong@baylibre.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/clockchips.h>
+#include <linux/sched_clock.h>
+
+/* TIMER1 used as tick
+ * TIMER2 used as clocksource
+ */
+
+/* Registers definitions */
+
+#define TIMER_LOAD_REG 0x0
+#define TIMER_CURR_REG 0x4
+#define TIMER_CTRL_REG 0x8
+#define TIMER_CLRINT_REG 0xC
+
+#define TIMER_BITS 24
+
+#define TIMER_MAX_VAL (BIT(TIMER_BITS) - 1)
+
+#define TIMER_PERIODIC BIT(6)
+#define TIMER_ENABLE BIT(7)
+
+#define TIMER_DIV1 (0)
+#define TIMER_DIV16 (1 << 2)
+#define TIMER_DIV256 (2 << 2)
+
+#define TIMER1_REG_OFFSET 0
+#define TIMER2_REG_OFFSET 0x20
+
+/* Clockevent & Clocksource data */
+
+struct oxnas_rps_timer {
+ struct clock_event_device clkevent;
+ void __iomem *clksrc_base;
+ void __iomem *clkevt_base;
+ unsigned long timer_period;
+ unsigned int timer_prescaler;
+ struct clk *clk;
+ int irq;
+};
+
+static irqreturn_t oxnas_rps_timer_irq(int irq, void *dev_id)
+{
+ struct oxnas_rps_timer *rps = dev_id;
+
+ writel_relaxed(0, rps->clkevt_base + TIMER_CLRINT_REG);
+
+ rps->clkevent.event_handler(&rps->clkevent);
+
+ return IRQ_HANDLED;
+}
+
+static void oxnas_rps_timer_config(struct oxnas_rps_timer *rps,
+ unsigned long period,
+ unsigned int periodic)
+{
+ uint32_t cfg = rps->timer_prescaler;
+
+ if (period)
+ cfg |= TIMER_ENABLE;
+
+ if (periodic)
+ cfg |= TIMER_PERIODIC;
+
+ writel_relaxed(period, rps->clkevt_base + TIMER_LOAD_REG);
+ writel_relaxed(cfg, rps->clkevt_base + TIMER_CTRL_REG);
+}
+
+static int oxnas_rps_timer_shutdown(struct clock_event_device *evt)
+{
+ struct oxnas_rps_timer *rps =
+ container_of(evt, struct oxnas_rps_timer, clkevent);
+
+ oxnas_rps_timer_config(rps, 0, 0);
+
+ return 0;
+}
+
+static int oxnas_rps_timer_set_periodic(struct clock_event_device *evt)
+{
+ struct oxnas_rps_timer *rps =
+ container_of(evt, struct oxnas_rps_timer, clkevent);
+
+ oxnas_rps_timer_config(rps, rps->timer_period, 1);
+
+ return 0;
+}
+
+static int oxnas_rps_timer_set_oneshot(struct clock_event_device *evt)
+{
+ struct oxnas_rps_timer *rps =
+ container_of(evt, struct oxnas_rps_timer, clkevent);
+
+ oxnas_rps_timer_config(rps, rps->timer_period, 0);
+
+ return 0;
+}
+
+static int oxnas_rps_timer_next_event(unsigned long delta,
+ struct clock_event_device *evt)
+{
+ struct oxnas_rps_timer *rps =
+ container_of(evt, struct oxnas_rps_timer, clkevent);
+
+ oxnas_rps_timer_config(rps, delta, 0);
+
+ return 0;
+}
+
+static int __init oxnas_rps_clockevent_init(struct oxnas_rps_timer *rps)
+{
+ ulong clk_rate = clk_get_rate(rps->clk);
+ ulong timer_rate;
+
+ /* Start with prescaler 1 */
+ rps->timer_prescaler = TIMER_DIV1;
+ rps->timer_period = DIV_ROUND_UP(clk_rate, HZ);
+ timer_rate = clk_rate;
+
+ if (rps->timer_period > TIMER_MAX_VAL) {
+ rps->timer_prescaler = TIMER_DIV16;
+ timer_rate = clk_rate / 16;
+ rps->timer_period = DIV_ROUND_UP(timer_rate, HZ);
+ }
+ if (rps->timer_period > TIMER_MAX_VAL) {
+ rps->timer_prescaler = TIMER_DIV256;
+ timer_rate = clk_rate / 256;
+ rps->timer_period = DIV_ROUND_UP(timer_rate, HZ);
+ }
+
+ rps->clkevent.name = "oxnas-rps";
+ rps->clkevent.features = CLOCK_EVT_FEAT_PERIODIC |
+ CLOCK_EVT_FEAT_ONESHOT |
+ CLOCK_EVT_FEAT_DYNIRQ;
+ rps->clkevent.tick_resume = oxnas_rps_timer_shutdown;
+ rps->clkevent.set_state_shutdown = oxnas_rps_timer_shutdown;
+ rps->clkevent.set_state_periodic = oxnas_rps_timer_set_periodic;
+ rps->clkevent.set_state_oneshot = oxnas_rps_timer_set_oneshot;
+ rps->clkevent.set_next_event = oxnas_rps_timer_next_event;
+ rps->clkevent.rating = 200;
+ rps->clkevent.cpumask = cpu_possible_mask;
+ rps->clkevent.irq = rps->irq;
+ clockevents_config_and_register(&rps->clkevent,
+ timer_rate,
+ 1,
+ TIMER_MAX_VAL);
+
+ pr_info("Registered clock event rate %luHz prescaler %x period %lu\n",
+ clk_rate,
+ rps->timer_prescaler,
+ rps->timer_period);
+
+ return 0;
+}
+
+/* Clocksource */
+
+static void __iomem *timer_sched_base;
+
+static u64 notrace oxnas_rps_read_sched_clock(void)
+{
+ return ~readl_relaxed(timer_sched_base);
+}
+
+static int __init oxnas_rps_clocksource_init(struct oxnas_rps_timer *rps)
+{
+ ulong clk_rate = clk_get_rate(rps->clk);
+ int ret;
+
+ /* use prescale 16 */
+ clk_rate = clk_rate / 16;
+
+ writel_relaxed(TIMER_MAX_VAL, rps->clksrc_base + TIMER_LOAD_REG);
+ writel_relaxed(TIMER_PERIODIC | TIMER_ENABLE | TIMER_DIV16,
+ rps->clksrc_base + TIMER_CTRL_REG);
+
+ timer_sched_base = rps->clksrc_base + TIMER_CURR_REG;
+ sched_clock_register(oxnas_rps_read_sched_clock,
+ TIMER_BITS, clk_rate);
+ ret = clocksource_mmio_init(timer_sched_base,
+ "oxnas_rps_clocksource_timer",
+ clk_rate, 250, TIMER_BITS,
+ clocksource_mmio_readl_down);
+ if (WARN_ON(ret)) {
+ pr_err("can't register clocksource\n");
+ return ret;
+ }
+
+ pr_info("Registered clocksource rate %luHz\n", clk_rate);
+
+ return 0;
+}
+
+static void __init oxnas_rps_timer_init(struct device_node *np)
+{
+ struct oxnas_rps_timer *rps;
+ void __iomem *base;
+ int ret;
+
+ rps = kzalloc(sizeof(*rps), GFP_KERNEL);
+ if (!rps) {
+ pr_err("Failed to allocate rps structure\n");
+ return;
+ }
+
+ rps->clk = of_clk_get(np, 0);
+ if (WARN_ON(IS_ERR(rps->clk)))
+ goto err_alloc;
+
+ if (WARN_ON(clk_prepare_enable(rps->clk)))
+ goto err_clk;
+
+ base = of_iomap(np, 0);
+ if (WARN_ON(!base))
+ goto err_clk_prepare;
+
+ rps->irq = irq_of_parse_and_map(np, 0);
+ if (WARN_ON(rps->irq < 0))
+ goto err_iomap;
+
+ rps->clkevt_base = base + TIMER1_REG_OFFSET;
+ rps->clksrc_base = base + TIMER2_REG_OFFSET;
+
+ /* Disable timers */
+ writel_relaxed(0, rps->clkevt_base + TIMER_CTRL_REG);
+ writel_relaxed(0, rps->clksrc_base + TIMER_CTRL_REG);
+ writel_relaxed(0, rps->clkevt_base + TIMER_LOAD_REG);
+ writel_relaxed(0, rps->clksrc_base + TIMER_LOAD_REG);
+ writel_relaxed(0, rps->clkevt_base + TIMER_CLRINT_REG);
+ writel_relaxed(0, rps->clksrc_base + TIMER_CLRINT_REG);
+
+ ret = request_irq(rps->irq, oxnas_rps_timer_irq,
+ IRQF_TIMER | IRQF_IRQPOLL,
+ "rps-timer", rps);
+ if (WARN_ON(ret))
+ goto err_iomap;
+
+ ret = oxnas_rps_clocksource_init(rps);
+ if (ret)
+ goto err_irqreq;
+
+ ret = oxnas_rps_clockevent_init(rps);
+ if (ret)
+ goto err_irqreq;
+
+ return;
+
+err_irqreq:
+ free_irq(rps->irq, rps);
+err_iomap:
+ iounmap(base);
+err_clk_prepare:
+ clk_disable_unprepare(rps->clk);
+err_clk:
+ clk_put(rps->clk);
+err_alloc:
+ kfree(rps);
+}
+
+CLOCKSOURCE_OF_DECLARE(ox810se_rps,
+ "oxsemi,ox810se-rps-timer", oxnas_rps_timer_init);
--
1.9.1