clk: Add support for rate table based dividers

Some divider clks do not have any obvious relationship
between the divider and the value programmed in the
register. For instance, say a value of 1 could signify divide
by 6 and a value of 2 could signify divide by 4 etc.
Also there are dividers where not all values possible
based on the bitfield width are valid. For instance
a 3 bit wide bitfield can be used to program a value
from 0 to 7. However its possible that only 0 to 4
are valid values.

All these cases need the platform code to pass a simple
table of divider/value tuple, so the framework knows
the exact value to be written based on the divider
calculation and can also do better error checking.

This patch adds support for such rate table based
dividers and as part of the support adds a new
registration function 'clk_register_divider_table()'
and a new macro for static definition
'DEFINE_CLK_DIVIDER_TABLE'.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 4a0b483986c3..79caee9f1489 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -203,6 +203,11 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
                 void __iomem *reg, u8 bit_idx,
                 u8 clk_gate_flags, spinlock_t *lock);
 
+struct clk_div_table {
+        unsigned int    val;
+        unsigned int    div;
+};
+
 /**
  * struct clk_divider - adjustable divider clock
  *
@@ -210,6 +215,7 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
  * @reg:        register containing the divider
  * @shift:      shift to the divider bit field
  * @width:      width of the divider bit field
+ * @table:      array of value/divider pairs, last entry should have div = 0
  * @lock:       register lock
  *
  * Clock with an adjustable divider affecting its output frequency.  Implements
@@ -229,6 +235,7 @@ struct clk_divider {
         u8              shift;
         u8              width;
         u8              flags;
+        const struct clk_div_table      *table;
         spinlock_t      *lock;
 };
 
@@ -240,6 +247,11 @@ struct clk *clk_register_divider(struct device *dev, const char *name,
                 const char *parent_name, unsigned long flags,
                 void __iomem *reg, u8 shift, u8 width,
                 u8 clk_divider_flags, spinlock_t *lock);
+struct clk *clk_register_divider_table(struct device *dev, const char *name,
+                const char *parent_name, unsigned long flags,
+                void __iomem *reg, u8 shift, u8 width,
+                u8 clk_divider_flags, const struct clk_div_table *table,
+                spinlock_t *lock);
 
 /**
  * struct clk_mux - multiplexer clock