On 03/09/2016 11:24 AM, Neil Armstrong wrote:
Some vendor variants can implement norrower counter width, add
an optional DT property changing the clocksource width and the
clockevent mask, but keeping 32bit as default for legacy interface.

Signed-off-by: Neil Armstrong <[email protected]>
---
  drivers/clocksource/timer-sp804.c | 38 +++++++++++++++++++++++++++-----------
  include/clocksource/timer-sp804.h | 11 ++++++-----
  2 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/drivers/clocksource/timer-sp804.c 
b/drivers/clocksource/timer-sp804.c
index 5f45b9a..8acf524 100644
--- a/drivers/clocksource/timer-sp804.c
+++ b/drivers/clocksource/timer-sp804.c
@@ -80,7 +80,8 @@ void __init sp804_timer_disable(void __iomem *base)
  void __init __sp804_clocksource_and_sched_clock_init(void __iomem *base,
                                                     const char *name,
                                                     struct clk *clk,
-                                                    int use_sched_clock)
+                                                    int use_sched_clock,
+                                                    unsigned width)
  {
        long rate;

@@ -93,6 +94,9 @@ void __init __sp804_clocksource_and_sched_clock_init(void 
__iomem *base,
                }
        }

+       if (!width || width > 32)
+               width = 32;
+

check comment below in the caller function.

        rate = sp804_get_clock_rate(clk);

        if (rate < 0)
@@ -106,11 +110,11 @@ void __init __sp804_clocksource_and_sched_clock_init(void 
__iomem *base,
                base + TIMER_CTRL);

        clocksource_mmio_init(base + TIMER_VALUE, name,
-               rate, 200, 32, clocksource_mmio_readl_down);
+               rate, 200, width, clocksource_mmio_readl_down);

        if (use_sched_clock) {
                sched_clock_base = base;
-               sched_clock_register(sp804_read, 32, rate);
+               sched_clock_register(sp804_read, width, rate);
        }
  }

@@ -186,7 +190,9 @@ static struct irqaction sp804_timer_irq = {
        .dev_id         = &sp804_clockevent,
  };

-void __init __sp804_clockevents_init(void __iomem *base, unsigned int irq, 
struct clk *clk, const char *name)
+void __init __sp804_clockevents_init(void __iomem *base, unsigned int irq,
+                                    struct clk *clk, const char *name,
+                                    unsigned width)
  {
        struct clock_event_device *evt = &sp804_clockevent;
        long rate;
@@ -199,6 +205,9 @@ void __init __sp804_clockevents_init(void __iomem *base, 
unsigned int irq, struc
                return;
        }

+       if (!width || width > 32)
+               width = 32;

Check comment below in the caller function.

        rate = sp804_get_clock_rate(clk);
        if (rate < 0)
                return;
@@ -212,7 +221,7 @@ void __init __sp804_clockevents_init(void __iomem *base, 
unsigned int irq, struc
        writel(0, base + TIMER_CTRL);

        setup_irq(irq, &sp804_timer_irq);
-       clockevents_config_and_register(evt, rate, 0xf, 0xffffffff);
+       clockevents_config_and_register(evt, rate, 0xf, GENMASK(width-1, 0));

This GENMASK is strange here. Nothing else than this ?

  }

  static void __init sp804_of_init(struct device_node *np)
@@ -223,6 +232,7 @@ static void __init sp804_of_init(struct device_node *np)
        u32 irq_num = 0;
        struct clk *clk1, *clk2;
        const char *name = of_get_property(np, "compatible", NULL);
+       u32 width = 32;

        base = of_iomap(np, 0);
        if (WARN_ON(!base))
@@ -254,14 +264,19 @@ static void __init sp804_of_init(struct device_node *np)
        if (irq <= 0)
                goto err;

+       /* Some vendor variants can have a different counter width */
+       of_property_read_u32(np, "arm,timer-width", &width);
+

Better to do the sanity check when the value is read.

Here, you can default to 32 if the width is 0 instead of initializing to 32 then read the property and call __sp804_clockevents_init which in turn check zero or more and set it to 32 again.

        of_property_read_u32(np, "arm,sp804-has-irq", &irq_num);
        if (irq_num == 2) {
-               __sp804_clockevents_init(base + TIMER_2_BASE, irq, clk2, name);
-               __sp804_clocksource_and_sched_clock_init(base, name, clk1, 1);
+               __sp804_clockevents_init(base + TIMER_2_BASE, irq,
+                                        clk2, name, width);
+               __sp804_clocksource_and_sched_clock_init(base, name,
+                                                        clk1, 1, width);
        } else {
-               __sp804_clockevents_init(base, irq, clk1 , name);
+               __sp804_clockevents_init(base, irq, clk1, name, width);
                __sp804_clocksource_and_sched_clock_init(base + TIMER_2_BASE,
-                                                        name, clk2, 1);
+                                                        name, clk2, 1, width);
        }
        initialized = true;

@@ -293,13 +308,14 @@ static void __init integrator_cp_of_init(struct 
device_node *np)
                goto err;

        if (!init_count)
-               __sp804_clocksource_and_sched_clock_init(base, name, clk, 0);
+               __sp804_clocksource_and_sched_clock_init(base, name,
+                                                        clk, 0, 32);
        else {
                irq = irq_of_parse_and_map(np, 0);
                if (irq <= 0)
                        goto err;

-               __sp804_clockevents_init(base, irq, clk, name);
+               __sp804_clockevents_init(base, irq, clk, name, 32);
        }

        init_count++;
diff --git a/include/clocksource/timer-sp804.h 
b/include/clocksource/timer-sp804.h
index 1f8a1ca..ad71fcb 100644
--- a/include/clocksource/timer-sp804.h
+++ b/include/clocksource/timer-sp804.h
@@ -4,25 +4,26 @@
  struct clk;

  void __sp804_clocksource_and_sched_clock_init(void __iomem *,
-                                             const char *, struct clk *, int);
+                                             const char *, struct clk *,
+                                             int, unsigned);
  void __sp804_clockevents_init(void __iomem *, unsigned int,
-                             struct clk *, const char *);
+                             struct clk *, const char *, unsigned);
  void sp804_timer_disable(void __iomem *);

  static inline void sp804_clocksource_init(void __iomem *base, const char 
*name)
  {
-       __sp804_clocksource_and_sched_clock_init(base, name, NULL, 0);
+       __sp804_clocksource_and_sched_clock_init(base, name, NULL, 0, 32);
  }

  static inline void sp804_clocksource_and_sched_clock_init(void __iomem *base,
                                                          const char *name)
  {
-       __sp804_clocksource_and_sched_clock_init(base, name, NULL, 1);
+       __sp804_clocksource_and_sched_clock_init(base, name, NULL, 1, 32);
  }

  static inline void sp804_clockevents_init(void __iomem *base, unsigned int 
irq, const char *name)
  {
-       __sp804_clockevents_init(base, irq, NULL, name);
+       __sp804_clockevents_init(base, irq, NULL, name, 32);

  }
  #endif



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