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Date: Wed, 7 Oct 2015 16:37:14 +0100
From: Mans Rullgard <mans@...sr.com>
To: Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] clocksource: mmio: add devicetree support
This implements the "clocksource-mmio" devicetree binding. It is
useful for devices that have a free-running counter requiring no
setup.
Signed-off-by: Mans Rullgard <mans@...sr.com>
---
Changed in v2:
- added sched_clock support
---
drivers/clocksource/mmio.c | 123 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 123 insertions(+)
diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
index 1593ade..b2cb3cc 100644
--- a/drivers/clocksource/mmio.c
+++ b/drivers/clocksource/mmio.c
@@ -5,9 +5,12 @@
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
+#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/errno.h>
#include <linux/init.h>
+#include <linux/of_address.h>
+#include <linux/sched_clock.h>
#include <linux/slab.h>
struct clocksource_mmio {
@@ -71,3 +74,123 @@ int __init clocksource_mmio_init(void __iomem *base, const char *name,
return clocksource_register_hz(&cs->clksrc, hz);
}
+
+#ifdef CONFIG_OF
+static void __iomem *sched_clock_mmio_reg;
+
+static u64 notrace sched_clock_mmio_readl_up(void)
+{
+ return (u64)readl_relaxed(sched_clock_mmio_reg);
+}
+
+static u64 notrace sched_clock_mmio_readl_down(void)
+{
+ return ~(u64)readl_relaxed(sched_clock_mmio_reg);
+}
+
+static u64 notrace sched_clock_mmio_readw_up(void)
+{
+ return (u64)readw_relaxed(sched_clock_mmio_reg);
+}
+
+static u64 notrace sched_clock_mmio_readw_down(void)
+{
+ return ~(u64)readw_relaxed(sched_clock_mmio_reg);
+}
+
+static void __init clocksource_mmio_of_setup(struct device_node *node)
+{
+ cycle_t (*csrc_read)(struct clocksource *);
+ u64 (*sched_read)(void);
+ void __iomem *reg;
+ struct clk *clk;
+ const char *name;
+ unsigned long rate;
+ bool count_down;
+ u32 rating;
+ u32 width;
+ u32 bits;
+ int err;
+
+ if (of_property_read_u32(node, "reg-io-width", &width)) {
+ pr_err("clocksource-mmio: register width not specified\n");
+ return;
+ }
+
+ if (of_property_read_u32(node, "clocksource-bits", &bits)) {
+ pr_err("clocksource-mmio: bits not specified\n");
+ return;
+ }
+
+ if (of_property_read_u32(node, "clocksource-rating", &rating)) {
+ pr_err("clocksource-mmio: rating not specified\n");
+ return;
+ }
+
+ count_down = of_property_read_bool(node, "clocksource-counts-down");
+
+ if (width == 2) {
+ if (count_down) {
+ csrc_read = clocksource_mmio_readw_down;
+ sched_read = sched_clock_mmio_readw_down;
+ } else {
+ csrc_read = clocksource_mmio_readw_up;
+ sched_read = sched_clock_mmio_readw_up;
+ }
+ } else if (width == 4) {
+ if (count_down) {
+ csrc_read = clocksource_mmio_readl_down;
+ sched_read = sched_clock_mmio_readl_down;
+ } else {
+ csrc_read = clocksource_mmio_readl_up;
+ sched_read = sched_clock_mmio_readl_up;
+ }
+ } else {
+ pr_err("clocksource-mmio: reg-io-width must be 2 or 4\n");
+ return;
+ }
+
+ clk = of_clk_get(node, 0);
+ if (IS_ERR(clk)) {
+ pr_err("clocksource-mmio: failed to get clock\n");
+ return;
+ }
+
+ if (clk_prepare_enable(clk)) {
+ pr_err("clocksource-mmio: failed to enable clock\n");
+ return;
+ }
+
+ rate = clk_get_rate(clk);
+ if (!rate) {
+ pr_err("clocksource-mmio: clock rate is zero\n");
+ clk_disable_unprepare(clk);
+ return;
+ }
+
+ reg = of_iomap(node, 0);
+ if (!reg) {
+ pr_err("clocksource-mmio: iomap failed\n");
+ clk_disable_unprepare(clk);
+ return;
+ }
+
+ if (of_property_read_string(node, "label", &name))
+ name = node->name;
+
+ err = clocksource_mmio_init(reg, name, rate, rating, bits, csrc_read);
+ if (err) {
+ pr_err("clocksource-mmio: failed to register clock source\n");
+ clk_disable_unprepare(clk);
+ iounmap(reg);
+ return;
+ }
+
+ if (of_property_read_bool(node, "linux,sched-clock")) {
+ sched_clock_mmio_reg = reg;
+ sched_clock_register(sched_read, bits, rate);
+ }
+}
+CLOCKSOURCE_OF_DECLARE(clocksource_mmio, "clocksource-mmio",
+ clocksource_mmio_of_setup);
+#endif
--
2.5.3
--
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