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 <m...@mansr.com>
---
drivers/clocksource/mmio.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 83 insertions(+)
diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
index 1593ade..a903720 100644
--- a/drivers/clocksource/mmio.c
+++ b/drivers/clocksource/mmio.c
@@ -5,9 +5,11 @@
* 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/slab.h>
struct clocksource_mmio {
@@ -71,3 +73,84 @@ int __init clocksource_mmio_init(void __iomem *base, const
char *name,
return clocksource_register_hz(&cs->clksrc, hz);
}
+
+#ifdef CONFIG_OF
+static void __init clocksource_mmio_of_setup(struct device_node *node)
+{
+ cycle_t (*read_fn)(struct clocksource *);
+ 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) {
+ read_fn = count_down ? clocksource_mmio_readw_down :
+ clocksource_mmio_readw_up;
+ } else if (width == 4) {
+ read_fn = count_down ? clocksource_mmio_readl_down :
+ clocksource_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, read_fn);
+ if (err) {
+ pr_err("clocksource-mmio: failed to register clock source\n");
+ clk_disable_unprepare(clk);
+ iounmap(reg);
+ }
+}
+CLOCKSOURCE_OF_DECLARE(clocksource_mmio, "clocksource-mmio",
+ clocksource_mmio_of_setup);
+#endif
--
2.5.3
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