[PATCH v4 2/3] clocksource: Add NPS400 timers driver

[Noam Camus <noamc@ezchip.com>]

From: Noam Camus <noamc@ezchip.com>

Add internal tick generator which is shared by all cores.
Each cluster of cores view it through dedicated address.
This is used for SMP system where all CPUs synced by same
clock source.

Signed-off-by: Noam Camus <noamc@ezchip.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
---
 .../bindings/timer/ezchip,nps400-timer.txt         |   15 ++++
 drivers/clocksource/Kconfig                        |   10 +++
 drivers/clocksource/Makefile                       |    1 +
 drivers/clocksource/timer-nps.c                    |   80 ++++++++++++++++++++
 4 files changed, 106 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/timer/ezchip,nps400-timer.txt
 create mode 100644 drivers/clocksource/timer-nps.c

diff --git a/Documentation/devicetree/bindings/timer/ezchip,nps400-timer.txt b/Documentation/devicetree/bindings/timer/ezchip,nps400-timer.txt
new file mode 100644
index 0000000..c8c03d7
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/ezchip,nps400-timer.txt
@@ -0,0 +1,15 @@
+NPS Network Processor
+
+Required properties:
+
+- compatible :	should be "ezchip,nps400-timer"
+
+Clocks required for compatible = "ezchip,nps400-timer":
+- clocks : Must contain a single entry describing the clock input
+
+Example:
+
+timer {
+	compatible = "ezchip,nps400-timer";
+	clocks = <&sysclk>;
+};
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 2eb5f0e..fa7be50 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -132,6 +132,16 @@ config CLKSRC_TI_32K
 	  This option enables support for Texas Instruments 32.768 Hz clocksource
 	  available on many OMAP-like platforms.
 
+config CLKSRC_NPS
+	bool "NPS400 clocksource driver" if COMPILE_TEST
+	depends on !PHYS_ADDR_T_64BIT
+	select CLKSRC_MMIO
+	select CLKSRC_OF if OF
+	help
+	  NPS400 clocksource support.
+	  Got 64 bit counter with update rate up to 1000MHz.
+	  This counter is accessed via couple of 32 bit memory mapped registers.
+
 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 56bd16e..056cffd 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -46,6 +46,7 @@ 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_CLKSRC_NPS)	+= timer-nps.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-nps.c b/drivers/clocksource/timer-nps.c
new file mode 100644
index 0000000..5a15970
--- /dev/null
+++ b/drivers/clocksource/timer-nps.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright(c) 2015 EZchip Technologies.
+ *
+ * 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.
+ *
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ */
+
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/cpu.h>
+#include <soc/nps/common.h>
+
+#define NPS_MSU_TICK_LOW	0xC8
+#define NPS_CLUSTER_OFFSET	8
+#define NPS_CLUSTER_NUM		16
+
+/* This array is per cluster of CPUs (Each NPS400 cluster got 256 CPUs) */
+static void *nps_msu_reg_low_addr[NPS_CLUSTER_NUM] __read_mostly;
+
+static unsigned long nps_timer_rate;
+
+static cycle_t nps_clksrc_read(struct clocksource *clksrc)
+{
+	int cluster = raw_smp_processor_id() >> NPS_CLUSTER_OFFSET;
+
+	return (cycle_t)ioread32be(nps_msu_reg_low_addr[cluster]);
+}
+
+static void __init nps_setup_clocksource(struct device_node *node,
+					 struct clk *clk)
+{
+	int ret, cluster;
+
+	for (cluster = 0; cluster < NPS_CLUSTER_NUM; cluster++)
+		nps_msu_reg_low_addr[cluster] =
+			nps_host_reg((cluster << NPS_CLUSTER_OFFSET),
+				 NPS_MSU_BLKID, NPS_MSU_TICK_LOW);
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		pr_err("Couldn't enable parent clock\n");
+		return;
+	}
+
+	nps_timer_rate = clk_get_rate(clk);
+
+	ret = clocksource_mmio_init(nps_msu_reg_low_addr, "EZnps-tick",
+				    nps_timer_rate, 301, 32, nps_clksrc_read);
+	if (ret) {
+		pr_err("Couldn't register clock source.\n");
+		clk_disable_unprepare(clk);
+	}
+}
+
+static void __init nps_timer_init(struct device_node *node)
+{
+	struct clk *clk;
+
+	clk = of_clk_get(node, 0);
+	if (IS_ERR(clk))
+		panic("Can't get timer clock");
+
+	nps_setup_clocksource(node, clk);
+}
+
+CLOCKSOURCE_OF_DECLARE(ezchip_nps400_clksrc, "ezchip,nps400-timer",
+		       nps_timer_init);
-- 
1.7.1