BCM2835: add clocksource driver

Signed-off-by: Carlo Caione <carlo.caione@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 95 insertions, 0 deletions

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 9d6d293ee3..09acdd74c5 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -2,6 +2,10 @@ config ARM_SMP_TWD
 	bool
 	depends on ARM && CPU_V7
 
+config CLOCKSOURCE_BCM2835
+	bool
+	depends on ARCH_BCM2835
+
 config CLOCKSOURCE_NOMADIK
 	bool
 	depends on ARM
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index bef465cea7..92d7c1344a 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -1,2 +1,3 @@
 obj-$(CONFIG_ARM_SMP_TWD) += arm_smp_twd.o
+obj-$(CONFIG_CLOCKSOURCE_BCM2835) += bcm2835.o
 obj-$(CONFIG_CLOCKSOURCE_NOMADIK) += nomadik.o
diff --git a/drivers/clocksource/bcm2835.c b/drivers/clocksource/bcm2835.c
new file mode 100644
index 0000000000..d5fe0f03a2
--- /dev/null
+++ b/drivers/clocksource/bcm2835.c
@@ -0,0 +1,90 @@
+/*
+ * Author: Carlo Caione <carlo@carlocaione.org>
+ *
+ * Based on clocksource for nomadik
+ *
+ * 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 <common.h>
+#include <clock.h>
+#include <io.h>
+#include <init.h>
+#include <driver.h>
+#include <errno.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+
+/* Registers */
+#define ST_CLO	0x04
+
+static __iomem void *stc_base;
+
+static uint64_t stc_read_cycles(void)
+{
+	return readl(stc_base + ST_CLO);
+}
+
+static struct clocksource bcm2835_stc = {
+	.read = stc_read_cycles,
+	.mask = CLOCKSOURCE_MASK(32),
+};
+
+static int bcm2835_cs_probe(struct device_d *dev)
+{
+	static struct clk *stc_clk;
+	u32 rate;
+	int ret;
+
+	stc_clk = clk_get(dev, NULL);
+	if (IS_ERR(stc_clk)) {
+		ret = PTR_ERR(stc_clk);
+		dev_err(dev, "clock not found: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_enable(stc_clk);
+	if (ret) {
+		dev_err(dev, "clock failed to enable: %d\n", ret);
+		clk_put(stc_clk);
+		return ret;
+	}
+
+	rate = clk_get_rate(stc_clk);
+	stc_base = dev_request_mem_region(dev, 0);
+
+	clocks_calc_mult_shift(&bcm2835_stc.mult, &bcm2835_stc.shift, rate, NSEC_PER_SEC, 60);
+	init_clock(&bcm2835_stc);
+
+	return 0;
+}
+
+static __maybe_unused struct of_device_id bcm2835_cs_dt_ids[] = {
+	{
+		.compatible = "brcm,bcm2835-system-timer",
+	}, {
+		/* sentinel */
+	}
+};
+
+static struct driver_d bcm2835_cs_driver = {
+	.name = "bcm2835-cs",
+	.probe = bcm2835_cs_probe,
+	.of_compatible = DRV_OF_COMPAT(bcm2835_cs_dt_ids),
+};
+
+static int bcm2835_cs_init(void)
+{
+	return platform_driver_register(&bcm2835_cs_driver);
+}
+coredevice_initcall(bcm2835_cs_init);