ARM: OMAP2+: Add device-tree support for 32kHz counter

For OMAP devices, the 32kHz counter is the default clock-source for the kernel.
However, this is not the only possible clock-source the kernel can use for OMAP
devices.

When booting with device-tree, if the 32kHz counter is the desired clock-source
for the kernel, then parse the device-tree blob to ensure that the counter is
present and if so map memory for the counter using the device-tree of_iomap()
function so we are no longer reliant on the OMAP HWMOD framework to do this for
us.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>

1 files changed, 27 insertions, 1 deletions

diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
index 92447cd7a41a..0758bae3a57a 100644
--- a/arch/arm/mach-omap2/timer.c
+++ b/arch/arm/mach-omap2/timer.c
@@ -159,6 +159,11 @@ static struct of_device_id omap_timer_match[] __initdata = {
         { }
 };
 
+static struct of_device_id omap_counter_match[] __initdata = {
+        { .compatible = "ti,omap-counter32k", },
+        { }
+};
+
 /**
  * omap_get_timer_dt - get a timer using device-tree
  * @match       - device-tree match structure for matching a device type
@@ -377,11 +382,26 @@ static u32 notrace dmtimer_read_sched_clock(void)
 static int __init omap2_sync32k_clocksource_init(void)
 {
         int ret;
+        struct device_node *np = NULL;
         struct omap_hwmod *oh;
         void __iomem *vbase;
         const char *oh_name = "counter_32k";
 
         /*
+         * If device-tree is present, then search the DT blob
+         * to see if the 32kHz counter is supported.
+         */
+        if (of_have_populated_dt()) {
+                np = omap_get_timer_dt(omap_counter_match, NULL);
+                if (!np)
+                        return -ENODEV;
+
+                of_property_read_string_index(np, "ti,hwmods", 0, &oh_name);
+                if (!oh_name)
+                        return -ENODEV;
+        }
+
+        /*
          * First check hwmod data is available for sync32k counter
          */
         oh = omap_hwmod_lookup(oh_name);
@@ -390,7 +410,13 @@ static int __init omap2_sync32k_clocksource_init(void)
 
         omap_hwmod_setup_one(oh_name);
 
-        vbase = omap_hwmod_get_mpu_rt_va(oh);
+        if (np) {
+                vbase = of_iomap(np, 0);
+                of_node_put(np);
+        } else {
+                vbase = omap_hwmod_get_mpu_rt_va(oh);
+        }
+
         if (!vbase) {
                 pr_warn("%s: failed to get counter_32k resource\n", __func__);
                 return -ENXIO;