irqchip/bcm2836: Fix initialization of the LOCAL_IRQ_CNT timers
The irqchip's register area includes the the setup for the timer's
scaling factors, and for the platform we want a fixed configuration of
these registers.
Signed-off-by: Eric Anholt <eric@anholt.net>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Lee Jones <lee@kernel.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-rpi-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1451166444-11044-2-git-send-email-eric@anholt.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/drivers/irqchip/irq-bcm2836.c b/drivers/irqchip/irq-bcm2836.c
index f687082..6ec125e 100644
--- a/drivers/irqchip/irq-bcm2836.c
+++ b/drivers/irqchip/irq-bcm2836.c
@@ -21,6 +21,9 @@
#include <linux/irqdomain.h>
#include <asm/exception.h>
+#define LOCAL_CONTROL 0x000
+#define LOCAL_PRESCALER 0x008
+
/*
* The low 2 bits identify the CPU that the GPU IRQ goes to, and the
* next 2 bits identify the CPU that the GPU FIQ goes to.
@@ -237,6 +240,27 @@
#endif
}
+/*
+ * The LOCAL_IRQ_CNT* timer firings are based off of the external
+ * oscillator with some scaling. The firmware sets up CNTFRQ to
+ * report 19.2Mhz, but doesn't set up the scaling registers.
+ */
+static void bcm2835_init_local_timer_frequency(void)
+{
+ /*
+ * Set the timer to source from the 19.2Mhz crystal clock (bit
+ * 8 unset), and only increment by 1 instead of 2 (bit 9
+ * unset).
+ */
+ writel(0, intc.base + LOCAL_CONTROL);
+
+ /*
+ * Set the timer prescaler to 1:1 (timer freq = input freq *
+ * 2**31 / prescaler)
+ */
+ writel(0x80000000, intc.base + LOCAL_PRESCALER);
+}
+
static int __init bcm2836_arm_irqchip_l1_intc_of_init(struct device_node *node,
struct device_node *parent)
{
@@ -246,6 +270,8 @@
node->full_name);
}
+ bcm2835_init_local_timer_frequency();
+
intc.domain = irq_domain_add_linear(node, LAST_IRQ + 1,
&bcm2836_arm_irqchip_intc_ops,
NULL);
