[PATCH 2/6] clocksource: add lpc32xx timer driver

Joachim Eastwood
2015-04-01T21:20:39Z

Add support for using the NXP LPC timer as clocksource and
clock event. These timers are present on many NXP devices
including LPC32xx, LPC17xx, LPC18xx and LPC43xx.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
---
drivers/clocksource/Kconfig | 10 ++
drivers/clocksource/Makefile | 1 +
drivers/clocksource/time-lpc32xx.c | 249 +++++++++++++++++++++++++++++++++++++
3 files changed, 260 insertions(+)
create mode 100644 drivers/clocksource/time-lpc32xx.c

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index a0b036ccb118..5fa8a28ebf35 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -106,6 +106,16 @@ config CLKSRC_EFM32
Support to use the timers of EFM32 SoCs as clock source and clock
event device.

+config CLKSRC_LPC32XX
+ bool "Clocksource for NXP's LPC SoC series" if !ARCH_LPC18XX
+ depends on OF && ARM && (ARCH_LPC18XX || COMPILE_TEST)
+ select CLKSRC_MMIO
+ default ARCH_LPC18XX
+ help
+ Support to use the timers of LPC SoCs as clock source and clock
+ event device. These timers are present on many NXP devices
+ including LPC32xx, LPC17xx, LPC18xx and LPC43xx.
+
config ARM_ARCH_TIMER
bool
select CLKSRC_OF if OF
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 752d5c70b0ef..c3f0ae067802 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_ARCH_BCM_MOBILE) += bcm_kona_timer.o
obj-$(CONFIG_CADENCE_TTC_TIMER) += cadence_ttc_timer.o
obj-$(CONFIG_CLKSRC_EFM32) += time-efm32.o
obj-$(CONFIG_CLKSRC_EXYNOS_MCT) += exynos_mct.o
+obj-$(CONFIG_CLKSRC_LPC32XX) += time-lpc32xx.o
obj-$(CONFIG_CLKSRC_SAMSUNG_PWM) += samsung_pwm_timer.o
obj-$(CONFIG_FSL_FTM_TIMER) += fsl_ftm_timer.o
obj-$(CONFIG_VF_PIT_TIMER) += vf_pit_timer.o
diff --git a/drivers/clocksource/time-lpc32xx.c b/drivers/clocksource/time-lpc32xx.c
new file mode 100644
index 000000000000..294fb0bcb712
--- /dev/null
+++ b/drivers/clocksource/time-lpc32xx.c
@@ -0,0 +1,249 @@
+/*
+ * Clocksource driver for NXP LPC32xx/18xx/43xx timer
+ *
+ * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
+ *
+ * Based on:
+ * time-efm32 Copyright (C) 2013 Pengutronix
+ * mach-lpc32xx/timer.c Copyright (C) 2009 - 2010 NXP Semiconductors
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#define LPC32XX_TIMER_IR 0x000
+#define LPC32XX_TIMER_IR_MR0INT BIT(0)
+#define LPC32XX_TIMER_TCR 0x004
+#define LPC32XX_TIMER_TCR_CEN BIT(0)
+#define LPC32XX_TIMER_TCR_CRST BIT(1)
+#define LPC32XX_TIMER_TC 0x008
+#define LPC32XX_TIMER_PR 0x00c
+#define LPC32XX_TIMER_MCR 0x014
+#define LPC32XX_TIMER_MCR_MR0I BIT(0)
+#define LPC32XX_TIMER_MCR_MR0R BIT(1)
+#define LPC32XX_TIMER_MCR_MR0S BIT(2)
+#define LPC32XX_TIMER_MR0 0x018
+
+struct lpc32xx_clock_event_ddata {
+ struct clock_event_device evtdev;
+ void __iomem *base;
+};
+
+static int lpc32xx_clkevt_next_event(unsigned long delta,
+ struct clock_event_device *evtdev)
+{
+ struct lpc32xx_clock_event_ddata *ddata =
+ container_of(evtdev, struct lpc32xx_clock_event_ddata, evtdev);
+
+ writel_relaxed(LPC32XX_TIMER_TCR_CRST, ddata->base + LPC32XX_TIMER_TCR);
+ writel_relaxed(delta, ddata->base + LPC32XX_TIMER_PR);
+ writel_relaxed(LPC32XX_TIMER_TCR_CEN, ddata->base + LPC32XX_TIMER_TCR);
+
+ return 0;
+}
+
+static void lpc32xx_clkevt_mode(enum clock_event_mode mode,
+ struct clock_event_device *evtdev)
+{
+ struct lpc32xx_clock_event_ddata *ddata =
+ container_of(evtdev, struct lpc32xx_clock_event_ddata, evtdev);
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ WARN_ON(1);
+ break;
+
+ case CLOCK_EVT_MODE_ONESHOT:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ /*
+ * Disable the timer. When using oneshot, we must also
+ * disable the timer to wait for the first call to
+ * set_next_event().
+ */
+ writel_relaxed(0, ddata->base + LPC32XX_TIMER_TCR);
+ break;
+
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_RESUME:
+ break;
+ }
+}
+
+static irqreturn_t lpc32xx_clock_event_handler(int irq, void *dev_id)
+{
+ struct lpc32xx_clock_event_ddata *ddata = dev_id;
+
+ /* Clear match */
+ writel_relaxed(LPC32XX_TIMER_IR_MR0INT, ddata->base + LPC32XX_TIMER_IR);
+
+ ddata->evtdev.event_handler(&ddata->evtdev);
+
+ return IRQ_HANDLED;
+}
+
+static struct lpc32xx_clock_event_ddata lpc32xx_clk_event_ddata = {
+ .evtdev = {
+ .name = "lpc3250 clockevent",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .rating = 300,
+ .set_next_event = lpc32xx_clkevt_next_event,
+ .set_mode = lpc32xx_clkevt_mode,
+ },
+};
+
+static struct irqaction lpc32xx_clock_event_irq = {
+ .name = "lpc3250 clockevent",
+ .flags = IRQF_TIMER | IRQF_IRQPOLL,
+ .handler = lpc32xx_clock_event_handler,
+ .dev_id = &lpc32xx_clk_event_ddata,
+};
+
+static int __init lpc32xx_clocksource_init(struct device_node *np)
+{
+ void __iomem *base;
+ unsigned long rate;
+ struct clk *clk;
+ int ret;
+
+ clk = of_clk_get(np, 0);
+ if (IS_ERR(clk)) {
+ pr_err("%s: clock get failed (%lu)\n", __func__, PTR_ERR(clk));
+ return PTR_ERR(clk);
+ }
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ pr_err("%s: clock enable failed (%d)\n", __func__, ret);
+ goto err_clk_enable;
+ }
+
+ rate = clk_get_rate(clk);
+
+ base = of_iomap(np, 0);
+ if (!base) {
+ pr_err("%s: unable to map registers\n", __func__);
+ ret = -EADDRNOTAVAIL;
+ goto err_iomap;
+ }
+
+ writel_relaxed(LPC32XX_TIMER_TCR_CRST, base + LPC32XX_TIMER_TCR);
+ writel_relaxed(0, base + LPC32XX_TIMER_PR);
+ writel_relaxed(0, base + LPC32XX_TIMER_MCR);
+ writel_relaxed(LPC32XX_TIMER_TCR_CEN, base + LPC32XX_TIMER_TCR);
+
+ ret = clocksource_mmio_init(base + LPC32XX_TIMER_TC, "lpc3250 timer",
+ rate, 300, 32, clocksource_mmio_readl_up);
+ if (ret) {
+ pr_err("failed to init clocksource (%d)\n", ret);
+ goto err_clocksource_init;
+ }
+
+ return 0;
+
+err_clocksource_init:
+ iounmap(base);
+err_iomap:
+ clk_disable_unprepare(clk);
+err_clk_enable:
+ clk_put(clk);
+ return ret;
+}
+
+static int __init lpc32xx_clockevent_init(struct device_node *np)
+{
+ void __iomem *base;
+ unsigned long rate;
+ struct clk *clk;
+ int ret, irq;
+
+ clk = of_clk_get(np, 0);
+ if (IS_ERR(clk)) {
+ pr_err("%s: clock get failed (%lu)\n", __func__, PTR_ERR(clk));
+ return PTR_ERR(clk);
+ }
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ pr_err("%s: clock enable failed (%d)\n", __func__, ret);
+ goto err_clk_enable;
+ }
+
+ rate = clk_get_rate(clk);
+
+ base = of_iomap(np, 0);
+ if (!base) {
+ pr_err("%s: unable to map registers\n", __func__);
+ ret = -EADDRNOTAVAIL;
+ goto err_iomap;
+ }
+
+ irq = irq_of_parse_and_map(np, 0);
+ if (!irq) {
+ pr_err("%s: get irq failed\n", __func__);
+ ret = -ENOENT;
+ goto err_get_irq;
+ }
+
+ /* Initial timer setup */
+ writel_relaxed(0, base + LPC32XX_TIMER_TCR);
+ writel_relaxed(LPC32XX_TIMER_IR_MR0INT, base + LPC32XX_TIMER_IR);
+ writel_relaxed(1, base + LPC32XX_TIMER_MR0);
+ writel_relaxed(LPC32XX_TIMER_MCR_MR0I | LPC32XX_TIMER_MCR_MR0R |
+ LPC32XX_TIMER_MCR_MR0S, base + LPC32XX_TIMER_MCR);
+
+ lpc32xx_clk_event_ddata.base = base;
+
+ setup_irq(irq, &lpc32xx_clock_event_irq);
+
+ clockevents_config_and_register(&lpc32xx_clk_event_ddata.evtdev,
+ rate, 1, -1);
+
+ return 0;
+
+err_get_irq:
+ iounmap(base);
+err_iomap:
+ clk_disable_unprepare(clk);
+err_clk_enable:
+ clk_put(clk);
+ return ret;
+}
+
+/*
+ * This function asserts that we have exactly one clocksource and one
+ * clock_event_device in the end.
+ */
+static void __init lpc32xx_timer_init(struct device_node *np)
+{
+ static int has_clocksource, has_clockevent;
+ int ret;
+
+ if (!has_clocksource) {
+ ret = lpc32xx_clocksource_init(np);
+ if (!ret) {
+ has_clocksource = 1;
+ return;
+ }
+ }
+
+ if (!has_clockevent) {
+ ret = lpc32xx_clockevent_init(np);
+ if (!ret) {
+ has_clockevent = 1;
+ return;
+ }
+ }
+}
+CLOCKSOURCE_OF_DECLARE(lpc32xx_timer, "nxp,lpc3250-timer", lpc32xx_timer_init);
--
1.8.0