clk: ingenic: Add support for divider tables

Some clocks provided on Ingenic SoCs have dividers, whose hardware value
as written in the register cannot be expressed as an affine function
to the actual divider value.

For instance, for the CPU clock on the JZ4770, the dividers are coded as
follows:

    ------------------
    | Bits     | Div |
    ------------------
    | 0  0  0  |  1  |
    | 0  0  1  |  2  |
    | 0  1  0  |  3  |
    | 0  1  1  |  4  |
    | 1  0  0  |  6  |
    | 1  0  1  |  8  |
    | 1  1  0  | 12  |
    ------------------

To support this setup, we introduce a new field in the
ingenic_cgu_div_info structure that allows to specify the divider table.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

diff --git a/drivers/clk/ingenic/cgu.c b/drivers/clk/ingenic/cgu.c
index b80af61dc1f320ed88c7190cd47148faff300158..c8150cbd0894bc8903d743007a1cf4db8e2fd51f 100644 (file)
--- a/drivers/clk/ingenic/cgu.c
+++ b/drivers/clk/ingenic/cgu.c
@@ -384,8 +384,11 @@ ingenic_clk_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
                div_reg = readl(cgu->base + clk_info->div.reg);
                div = (div_reg >> clk_info->div.shift) &
                      GENMASK(clk_info->div.bits - 1, 0);
-               div += 1;
-               div *= clk_info->div.div;
+
+               if (clk_info->div.div_table)
+                       div = clk_info->div.div_table[div];
+               else
+                       div = (div + 1) * clk_info->div.div;
 
                rate /= div;
        } else if (clk_info->type & CGU_CLK_FIXDIV) {
@@ -395,16 +398,37 @@ ingenic_clk_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
        return rate;
 }
 
+static unsigned int
+ingenic_clk_calc_hw_div(const struct ingenic_cgu_clk_info *clk_info,
+                       unsigned int div)
+{
+       unsigned int i;
+
+       for (i = 0; i < (1 << clk_info->div.bits)
+                               && clk_info->div.div_table[i]; i++) {
+               if (clk_info->div.div_table[i] >= div)
+                       return i;
+       }
+
+       return i - 1;
+}
+
 static unsigned
 ingenic_clk_calc_div(const struct ingenic_cgu_clk_info *clk_info,
                     unsigned long parent_rate, unsigned long req_rate)
 {
-       unsigned div;
+       unsigned int div, hw_div;
 
        /* calculate the divide */
        div = DIV_ROUND_UP(parent_rate, req_rate);
 
-       /* and impose hardware constraints */
+       if (clk_info->div.div_table) {
+               hw_div = ingenic_clk_calc_hw_div(clk_info, div);
+
+               return clk_info->div.div_table[hw_div];
+       }
+
+       /* Impose hardware constraints */
        div = min_t(unsigned, div, 1 << clk_info->div.bits);
        div = max_t(unsigned, div, 1);
 
@@ -447,7 +471,7 @@ ingenic_clk_set_rate(struct clk_hw *hw, unsigned long req_rate,
        const struct ingenic_cgu_clk_info *clk_info;
        const unsigned timeout = 100;
        unsigned long rate, flags;
-       unsigned div, i;
+       unsigned int hw_div, div, i;
        u32 reg, mask;
        int ret = 0;
 
@@ -460,13 +484,18 @@ ingenic_clk_set_rate(struct clk_hw *hw, unsigned long req_rate,
                if (rate != req_rate)
                        return -EINVAL;
 
+               if (clk_info->div.div_table)
+                       hw_div = ingenic_clk_calc_hw_div(clk_info, div);
+               else
+                       hw_div = ((div / clk_info->div.div) - 1);
+
                spin_lock_irqsave(&cgu->lock, flags);
                reg = readl(cgu->base + clk_info->div.reg);
 
                /* update the divide */
                mask = GENMASK(clk_info->div.bits - 1, 0);
                reg &= ~(mask << clk_info->div.shift);
-               reg |= ((div / clk_info->div.div) - 1) << clk_info->div.shift;
+               reg |= hw_div << clk_info->div.shift;
 
                /* clear the stop bit */
                if (clk_info->div.stop_bit != -1)

diff --git a/drivers/clk/ingenic/cgu.h b/drivers/clk/ingenic/cgu.h
index e12716d8ce3cf13ef002a8159a99568178b625cc..8dcd83aeab84cdcbed60d7d3a3c4e796191524d9 100644 (file)
--- a/drivers/clk/ingenic/cgu.h
+++ b/drivers/clk/ingenic/cgu.h
@@ -88,6 +88,8 @@ struct ingenic_cgu_mux_info {
  *          isn't one
  * @busy_bit: the index of the busy bit within reg, or -1 if there isn't one
  * @stop_bit: the index of the stop bit within reg, or -1 if there isn't one
+ * @div_table: optional table to map the value read from the register to the
+ *             actual divider value
  */
 struct ingenic_cgu_div_info {
        unsigned reg;
@@ -97,6 +99,7 @@ struct ingenic_cgu_div_info {
        s8 ce_bit;
        s8 busy_bit;
        s8 stop_bit;
+       const u8 *div_table;
 };
 
 /**