This updates the clk-divider to Kernel code, but without power-of-two
divider support which we do not need yet. This also adds table based
divider support to the divider.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
drivers/clk/clk-divider.c | 191 ++++++++++++++++++++++++++++++++++++++--------
include/linux/clk.h | 3 +
2 files changed, 164 insertions(+), 30 deletions(-)
diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index bb8bcc1..9634bd3 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -20,61 +20,192 @@
#include <linux/clk.h>
#include <linux/err.h>
-static unsigned int clk_divider_maxdiv(struct clk_divider *div)
+#define div_mask(d) ((1 << ((d)->width)) - 1)
+
+static unsigned int _get_maxdiv(struct clk_divider *divider)
{
- if (div->flags & CLK_DIVIDER_ONE_BASED)
- return (1 << div->width) - 1;
- return 1 << div->width;
+ if (divider->flags & CLK_DIVIDER_ONE_BASED)
+ return div_mask(divider);
+ return div_mask(divider) + 1;
}
-static int clk_divider_set_rate(struct clk *clk, unsigned long rate,
+static unsigned int _get_table_div(const struct clk_div_table *table,
+ unsigned int val)
+{
+ const struct clk_div_table *clkt;
+
+ for (clkt = table; clkt->div; clkt++)
+ if (clkt->val == val)
+ return clkt->div;
+ return 0;
+}
+
+static unsigned int _get_div(struct clk_divider *divider, unsigned int val)
+{
+ if (divider->flags & CLK_DIVIDER_ONE_BASED)
+ return val;
+ if (divider->table)
+ return _get_table_div(divider->table, val);
+ return val + 1;
+}
+
+static unsigned int _get_table_val(const struct clk_div_table *table,
+ unsigned int div)
+{
+ const struct clk_div_table *clkt;
+
+ for (clkt = table; clkt->div; clkt++)
+ if (clkt->div == div)
+ return clkt->val;
+ return 0;
+}
+
+static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
+{
+ if (divider->flags & CLK_DIVIDER_ONE_BASED)
+ return div;
+ if (divider->table)
+ return _get_table_val(divider->table, div);
+ return div - 1;
+}
+
+static unsigned long clk_divider_recalc_rate(struct clk *clk,
unsigned long parent_rate)
{
- struct clk_divider *div = container_of(clk, struct clk_divider, clk);
- unsigned int val, divval;
+ struct clk_divider *divider = container_of(clk, struct clk_divider, clk);
+ unsigned int div, val;
+
+ val = readl(divider->reg) >> divider->shift;
+ val &= div_mask(divider);
+
+ div = _get_div(divider, val);
+
+ return parent_rate / div;
+}
+
+/*
+ * The reverse of DIV_ROUND_UP: The maximum number which
+ * divided by m is r
+ */
+#define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)
+
+static bool _is_valid_table_div(const struct clk_div_table *table,
+ unsigned int div)
+{
+ const struct clk_div_table *clkt;
+
+ for (clkt = table; clkt->div; clkt++)
+ if (clkt->div == div)
+ return true;
+ return false;
+}
+
+static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
+{
+ if (divider->table)
+ return _is_valid_table_div(divider->table, div);
+ return true;
+}
+
+static int clk_divider_bestdiv(struct clk *clk, unsigned long rate,
+ unsigned long *best_parent_rate)
+{
+ struct clk_divider *divider = container_of(clk, struct clk_divider, clk);
+ int i, bestdiv = 0;
+ unsigned long parent_rate, best = 0, now, maxdiv;
+ unsigned long parent_rate_saved = *best_parent_rate;
- if (rate > parent_rate)
- rate = parent_rate;
if (!rate)
rate = 1;
- divval = DIV_ROUND_UP(parent_rate, rate);
- if (divval > clk_divider_maxdiv(div))
- divval = clk_divider_maxdiv(div);
+ maxdiv = _get_maxdiv(divider);
- if (!(div->flags & CLK_DIVIDER_ONE_BASED))
- divval--;
+ if (!(clk->flags & CLK_SET_RATE_PARENT)) {
+ parent_rate = *best_parent_rate;
+ bestdiv = DIV_ROUND_UP(parent_rate, rate);
+ bestdiv = bestdiv == 0 ? 1 : bestdiv;
+ bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
+ return bestdiv;
+ }
- val = readl(div->reg);
- val &= ~(((1 << div->width) - 1) << div->shift);
- val |= divval << div->shift;
- writel(val, div->reg);
+ /*
+ * The maximum divider we can use without overflowing
+ * unsigned long in rate * i below
+ */
+ maxdiv = min(ULONG_MAX / rate, maxdiv);
+
+ for (i = 1; i <= maxdiv; i++) {
+ if (!_is_valid_div(divider, i))
+ continue;
+ if (rate * i == parent_rate_saved) {
+ /*
+ * It's the most ideal case if the requested rate can be
+ * divided from parent clock without needing to change
+ * parent rate, so return the divider immediately.
+ */
+ *best_parent_rate = parent_rate_saved;
+ return i;
+ }
+ parent_rate = clk_round_rate(clk_get_parent(clk),
+ MULT_ROUND_UP(rate, i));
+ now = parent_rate / i;
+ if (now <= rate && now > best) {
+ bestdiv = i;
+ best = now;
+ *best_parent_rate = parent_rate;
+ }
+ }
- return 0;
+ if (!bestdiv) {
+ bestdiv = _get_maxdiv(divider);
+ *best_parent_rate = clk_round_rate(clk_get_parent(clk), 1);
+ }
+
+ return bestdiv;
}
-static unsigned long clk_divider_recalc_rate(struct clk *clk,
- unsigned long parent_rate)
+static long clk_divider_round_rate(struct clk *clk, unsigned long rate,
+ unsigned long *parent_rate)
{
- struct clk_divider *div = container_of(clk, struct clk_divider, clk);
- unsigned int val;
+ int div;
- val = readl(div->reg) >> div->shift;
- val &= (1 << div->width) - 1;
+ div = clk_divider_bestdiv(clk, rate, parent_rate);
- if (div->flags & CLK_DIVIDER_ONE_BASED) {
- if (!val)
- val++;
+ return *parent_rate / div;
+}
+
+static int clk_divider_set_rate(struct clk *clk, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct clk_divider *divider = container_of(clk, struct clk_divider, clk);
+ unsigned int div, value;
+ u32 val;
+
+ if (clk->flags & CLK_SET_RATE_PARENT) {
+ unsigned long best_parent_rate = parent_rate;
+ div = clk_divider_bestdiv(clk, rate, &best_parent_rate);
+ clk_set_rate(clk_get_parent(clk), best_parent_rate);
} else {
- val++;
+ div = parent_rate / rate;
}
- return parent_rate / val;
+ value = _get_val(divider, div);
+
+ if (value > div_mask(divider))
+ value = div_mask(divider);
+
+ val = readl(divider->reg);
+ val &= ~(div_mask(divider) << divider->shift);
+ val |= value << divider->shift;
+ writel(val, divider->reg);
+
+ return 0;
}
struct clk_ops clk_divider_ops = {
.set_rate = clk_divider_set_rate,
.recalc_rate = clk_divider_recalc_rate,
+ .round_rate = clk_divider_round_rate,
};
struct clk *clk_divider(const char *name, const char *parent,
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 2704b0f..71b0466 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -240,6 +240,9 @@ struct clk_divider {
const char *parent;
#define CLK_DIVIDER_ONE_BASED (1 << 0)
unsigned flags;
+ const struct clk_div_table *table;
+ int max_div_index;
+ int table_size;
};
extern struct clk_ops clk_divider_ops;
--
1.9.0
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