[PATCH 09/11] clocksource: add TI 32.768 Hz counter driver
From: Felipe Balbi
Date: Tue Oct 06 2015 - 13:03:00 EST
Introduce a new clocksource driver for Texas
Instruments 32.768 Hz device which is available
on most OMAP-like devices.
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
---
drivers/clocksource/Kconfig | 7 +++
drivers/clocksource/Makefile | 1 +
drivers/clocksource/timer-ti-32k.c | 122 +++++++++++++++++++++++++++++++++++++
3 files changed, 130 insertions(+)
create mode 100644 drivers/clocksource/timer-ti-32k.c
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index a7726db13abb..98b2a9b9bfad 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -115,6 +115,13 @@ config CLKSRC_PISTACHIO
bool
select CLKSRC_OF
+config CLKSRC_TI_32K
+ bool "Texas Instruments 32.768 Hz Clocksource" if COMPILE_TEST
+ select CLKSRC_OF if OF
+ help
+ This option enables support for Texas Instruments 32.768 Hz clocksource
+ available on many OMAP-like platforms.
+
config CLKSRC_STM32
bool "Clocksource for STM32 SoCs" if !ARCH_STM32
depends on OF && ARM && (ARCH_STM32 || COMPILE_TEST)
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 5c00863c3e33..749abc3665b3 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -45,6 +45,7 @@ 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_CLKSRC_PISTACHIO) += time-pistachio.o
+obj-$(CONFIG_CLKSRC_TI_32K) += timer-ti-32k.o
obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
obj-$(CONFIG_ARM_GLOBAL_TIMER) += arm_global_timer.o
diff --git a/drivers/clocksource/timer-ti-32k.c b/drivers/clocksource/timer-ti-32k.c
new file mode 100644
index 000000000000..12e2ca7bcc49
--- /dev/null
+++ b/drivers/clocksource/timer-ti-32k.c
@@ -0,0 +1,122 @@
+/**
+ * timer-ti-32k.c - OMAP2 32k Timer Support
+ *
+ * Copyright (C) 2009 Nokia Corporation
+ *
+ * Update to use new clocksource/clockevent layers
+ * Author: Kevin Hilman, MontaVista Software, Inc. <source@xxxxxxxxxx>
+ * Copyright (C) 2007 MontaVista Software, Inc.
+ *
+ * Original driver:
+ * Copyright (C) 2005 Nokia Corporation
+ * Author: Paul Mundt <paul.mundt@xxxxxxxxx>
+ * Juha YrjÃlà <juha.yrjola@xxxxxxxxx>
+ * OMAP Dual-mode timer framework support by Timo Teras
+ *
+ * Some parts based off of TI's 24xx code:
+ *
+ * Copyright (C) 2004-2009 Texas Instruments, Inc.
+ *
+ * Roughly modelled after the OMAP1 MPU timer code.
+ * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@xxxxxx>
+ *
+ * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 of
+ * the License as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/init.h>
+#include <linux/time.h>
+#include <linux/sched_clock.h>
+#include <linux/clocksource.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+/*
+ * 32KHz clocksource ... always available, on pretty most chips except
+ * OMAP 730 and 1510. Other timers could be used as clocksources, with
+ * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
+ * but systems won't necessarily want to spend resources that way.
+ */
+
+#define OMAP2_32KSYNCNT_REV_OFF 0x0
+#define OMAP2_32KSYNCNT_REV_SCHEME (0x3 << 30)
+#define OMAP2_32KSYNCNT_CR_OFF_LOW 0x10
+#define OMAP2_32KSYNCNT_CR_OFF_HIGH 0x30
+
+struct ti_32k {
+ void __iomem *base;
+ void __iomem *counter;
+ struct clocksource cs;
+};
+#define to_ti_32k(cs) (container_of((cs), struct ti_32k, cs))
+
+static cycle_t ti_32k_read_cycles(struct clocksource *cs)
+{
+ struct ti_32k *ti = to_ti_32k(cs);
+
+ return (cycle_t)readl_relaxed(ti->counter);
+}
+
+static struct ti_32k ti_32k_timer = {
+ .cs = {
+ .name = "32k_counter",
+ .rating = 250,
+ .read = ti_32k_read_cycles,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS |
+ CLOCK_SOURCE_SUSPEND_NONSTOP,
+ },
+};
+
+static u64 notrace omap_32k_read_sched_clock(void)
+{
+ return ti_32k_read_cycles(&ti_32k_timer.cs);
+}
+
+static void __init ti_32k_timer_init(struct device_node *np)
+{
+ int ret;
+
+ ti_32k_timer.base = of_iomap(np, 0);
+ if (!ti_32k_timer.base) {
+ pr_err("Can't ioremap 32k timer base\n");
+ return;
+ }
+
+ ti_32k_timer.counter = ti_32k_timer.base;
+
+ /*
+ * 32k sync Counter IP register offsets vary between the highlander
+ * version and the legacy ones.
+ *
+ * The 'SCHEME' bits(30-31) of the revision register is used to identify
+ * the version.
+ */
+ if (readl_relaxed(ti_32k_timer.base + OMAP2_32KSYNCNT_REV_OFF) &
+ OMAP2_32KSYNCNT_REV_SCHEME)
+ ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_HIGH;
+ else
+ ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_LOW;
+
+ ret = clocksource_register_hz(&ti_32k_timer.cs, 32768);
+ if (ret) {
+ pr_err("32k_counter: can't register clocksource\n");
+ return;
+ }
+
+ sched_clock_register(omap_32k_read_sched_clock, 32, 32768);
+ pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
+}
+CLOCKSOURCE_OF_DECLARE(ti_32k_timer, "ti,omap-counter32k",
+ ti_32k_timer_init);
--
2.5.3
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