clk: mux: add CLK_MUX_HIWORD_MASK

In both Hisilicon & Rockchip Cortex-A9 based chips, they don't use the
paradigm of reading-changing-writing the register contents.
Instead they use a hiword mask to indicate the changed bits.

When b01 should be set as switching mux, it also needs to indicate
the change by setting hiword mask (b11 << 16).

The patch adds mux flag for this usage.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

2 files changed, 20 insertions, 2 deletions

diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
index 25b1734560d0..614444ca40cd 100644
--- a/drivers/clk/clk-mux.c
+++ b/drivers/clk/clk-mux.c
@@ -86,8 +86,12 @@ static int clk_mux_set_parent(struct clk_hw *hw, u8 index)
         if (mux->lock)
                 spin_lock_irqsave(mux->lock, flags);
 
-        val = readl(mux->reg);
-        val &= ~(mux->mask << mux->shift);
+        if (mux->flags & CLK_MUX_HIWORD_MASK) {
+                val = mux->mask << (mux->shift + 16);
+        } else {
+                val = readl(mux->reg);
+                val &= ~(mux->mask << mux->shift);
+        }
         val |= index << mux->shift;
         writel(val, mux->reg);
 
@@ -111,6 +115,15 @@ struct clk *clk_register_mux_table(struct device *dev, const char *name,
         struct clk_mux *mux;
         struct clk *clk;
         struct clk_init_data init;
+        u8 width = 0;
+
+        if (clk_mux_flags & CLK_MUX_HIWORD_MASK) {
+                width = fls(mask) - ffs(mask) + 1;
+                if (width + shift > 16) {
+                        pr_err("mux value exceeds LOWORD field\n");
+                        return ERR_PTR(-EINVAL);
+                }
+        }
 
         /* allocate the mux */
         mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 265f384f1e01..37ad97961e5a 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -299,6 +299,10 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
  * Flags:
  * CLK_MUX_INDEX_ONE - register index starts at 1, not 0
  * CLK_MUX_INDEX_BIT - register index is a single bit (power of two)
+ * CLK_MUX_HIWORD_MASK - The mux settings are only in lower 16-bit of this
+ *   register, and mask of mux bits are in higher 16-bit of this register.
+ *   While setting the mux bits, higher 16-bit should also be updated to
+ *   indicate changing mux bits.
  */
 struct clk_mux {
         struct clk_hw   hw;
@@ -312,6 +316,7 @@ struct clk_mux {
 
 #define CLK_MUX_INDEX_ONE               BIT(0)
 #define CLK_MUX_INDEX_BIT               BIT(1)
+#define CLK_MUX_HIWORD_MASK             BIT(2)
 
 extern const struct clk_ops clk_mux_ops;