xtensa: rearrange CCOUNT calibration

DT-enabled kernel should have a CPU node connected to a clock. This clock
is the CCOUNT clock. Use old platform_calibrate_ccount call as a fallback
when CPU node cannot be found or has no clock and in non-DT-enabled
configurations.

Drop no longer needed code that updates CPU clock-frequency property in
the DT; drop DT-related code from the platform_calibrate_ccount too.

Move of_clk_init to the top of time_init, so that clocks are initialized
before CCOUNT calibration is attempted.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

diff --git a/arch/xtensa/boot/dts/xtfpga.dtsi b/arch/xtensa/boot/dts/xtfpga.dtsi
index ded5698..91616a9 100644 (file)
--- a/arch/xtensa/boot/dts/xtfpga.dtsi
+++ b/arch/xtensa/boot/dts/xtfpga.dtsi
@@ -19,9 +19,7 @@
                cpu@0 {
                        compatible = "cdns,xtensa-cpu";
                        reg = <0>;
-                       /* Filled in by platform_setup from FPGA register
-                        * clock-frequency = <100000000>;
-                        */
+                       clocks = <&osc>;
                };
        };
 

diff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c
index 7ed6368..d61c846 100644 (file)
--- a/arch/xtensa/kernel/setup.c
+++ b/arch/xtensa/kernel/setup.c
@@ -23,7 +23,6 @@
 #include <linux/bootmem.h>
 #include <linux/kernel.h>
 #include <linux/percpu.h>
-#include <linux/clk-provider.h>
 #include <linux/cpu.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
@@ -249,7 +248,6 @@ void __init early_init_devtree(void *params)
 
 static int __init xtensa_device_probe(void)
 {
-       of_clk_init(NULL);
        of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
        return 0;
 }

diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index b9ad9fe..9a5bcd0 100644 (file)
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -12,6 +12,8 @@
  * Chris Zankel <chris@zankel.net>
  */
 
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/time.h>
@@ -134,16 +136,52 @@ void local_timer_setup(unsigned cpu)
                                        0xf, 0xffffffff);
 }
 
+#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
+#ifdef CONFIG_OF
+static void __init calibrate_ccount(void)
+{
+       struct device_node *cpu;
+       struct clk *clk;
+
+       cpu = of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu");
+       if (cpu) {
+               clk = of_clk_get(cpu, 0);
+               if (!IS_ERR(clk)) {
+                       ccount_freq = clk_get_rate(clk);
+                       return;
+               } else {
+                       pr_warn("%s: CPU input clock not found\n",
+                               __func__);
+               }
+       } else {
+               pr_warn("%s: CPU node not found in the device tree\n",
+                       __func__);
+       }
+
+       platform_calibrate_ccount();
+}
+#else
+static inline void calibrate_ccount(void)
+{
+       platform_calibrate_ccount();
+}
+#endif
+#endif
+
 void __init time_init(void)
 {
+       of_clk_init(NULL);
 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
        printk("Calibrating CPU frequency ");
-       platform_calibrate_ccount();
+       calibrate_ccount();
        printk("%d.%02d MHz\n", (int)ccount_freq/1000000,
                        (int)(ccount_freq/10000)%100);
 #else
        ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL;
 #endif
+       WARN(!ccount_freq,
+            "%s: CPU clock frequency is not set up correctly\n",
+            __func__);
        clocksource_register_hz(&ccount_clocksource, ccount_freq);
        local_timer_setup(0);
        setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction);

diff --git a/arch/xtensa/platforms/xtfpga/setup.c b/arch/xtensa/platforms/xtfpga/setup.c
index 99a38a6..e236df4 100644 (file)
--- a/arch/xtensa/platforms/xtfpga/setup.c
+++ b/arch/xtensa/platforms/xtfpga/setup.c
@@ -66,29 +66,6 @@ void __init platform_setup(char **cmdline)
 
 #ifdef CONFIG_OF
 
-static void __init update_clock_frequency(struct device_node *node)
-{
-       struct property *newfreq;
-       u32 freq;
-
-       if (!of_property_read_u32(node, "clock-frequency", &freq) && freq != 0)
-               return;
-
-       newfreq = kzalloc(sizeof(*newfreq) + sizeof(u32), GFP_KERNEL);
-       if (!newfreq)
-               return;
-       newfreq->value = newfreq + 1;
-       newfreq->length = sizeof(freq);
-       newfreq->name = kstrdup("clock-frequency", GFP_KERNEL);
-       if (!newfreq->name) {
-               kfree(newfreq);
-               return;
-       }
-
-       *(u32 *)newfreq->value = cpu_to_be32(*(u32 *)XTFPGA_CLKFRQ_VADDR);
-       of_update_property(node, newfreq);
-}
-
 static void __init xtfpga_clk_setup(struct device_node *np)
 {
        void __iomem *base = of_iomap(np, 0);
@@ -172,21 +149,7 @@ void platform_heartbeat(void)
 
 void __init platform_calibrate_ccount(void)
 {
-       long clk_freq = 0;
-#ifdef CONFIG_OF
-       struct device_node *cpu =
-               of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu");
-       if (cpu) {
-               u32 freq;
-               update_clock_frequency(cpu);
-               if (!of_property_read_u32(cpu, "clock-frequency", &freq))
-                       clk_freq = freq;
-       }
-#endif
-       if (!clk_freq)
-               clk_freq = *(long *)XTFPGA_CLKFRQ_VADDR;
-
-       ccount_freq = clk_freq;
+       ccount_freq = *(long *)XTFPGA_CLKFRQ_VADDR;
 }
 
 #endif