clk: at91: usb: propagate rate modification to the parent clk

The at91sam9n12 and at91sam9x5 usb clocks do not propagate rate
modification requests to their parents.
This causes a bug when the PLLB is left uninitialized by the bootloader
(PLL multiplier set to 0, or in other words, PLL rate = 0 Hz).

Implement the determinate_rate method and propagate the change rate
request to the parent clk.

Cc: <stable@vger.kernel.org> # v3.14+
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reported-by: Bo Shen <voice.shen@atmel.com>
Tested-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

diff --git a/drivers/clk/at91/clk-usb.c b/drivers/clk/at91/clk-usb.c
index a23ac0c..0b7c3e8 100644 (file)
--- a/drivers/clk/at91/clk-usb.c
+++ b/drivers/clk/at91/clk-usb.c
@@ -56,22 +56,55 @@ static unsigned long at91sam9x5_clk_usb_recalc_rate(struct clk_hw *hw,
        return DIV_ROUND_CLOSEST(parent_rate, (usbdiv + 1));
 }
 
-static long at91sam9x5_clk_usb_round_rate(struct clk_hw *hw, unsigned long rate,
-                                         unsigned long *parent_rate)
+static long at91sam9x5_clk_usb_determine_rate(struct clk_hw *hw,
+                                             unsigned long rate,
+                                             unsigned long min_rate,
+                                             unsigned long max_rate,
+                                             unsigned long *best_parent_rate,
+                                             struct clk_hw **best_parent_hw)
 {
-       unsigned long div;
+       struct clk *parent = NULL;
+       long best_rate = -EINVAL;
+       unsigned long tmp_rate;
+       int best_diff = -1;
+       int tmp_diff;
+       int i;
 
-       if (!rate)
-               return -EINVAL;
+       for (i = 0; i < __clk_get_num_parents(hw->clk); i++) {
+               int div;
 
-       if (rate >= *parent_rate)
-               return *parent_rate;
+               parent = clk_get_parent_by_index(hw->clk, i);
+               if (!parent)
+                       continue;
+
+               for (div = 1; div < SAM9X5_USB_MAX_DIV + 2; div++) {
+                       unsigned long tmp_parent_rate;
+
+                       tmp_parent_rate = rate * div;
+                       tmp_parent_rate = __clk_round_rate(parent,
+                                                          tmp_parent_rate);
+                       tmp_rate = DIV_ROUND_CLOSEST(tmp_parent_rate, div);
+                       if (tmp_rate < rate)
+                               tmp_diff = rate - tmp_rate;
+                       else
+                               tmp_diff = tmp_rate - rate;
+
+                       if (best_diff < 0 || best_diff > tmp_diff) {
+                               best_rate = tmp_rate;
+                               best_diff = tmp_diff;
+                               *best_parent_rate = tmp_parent_rate;
+                               *best_parent_hw = __clk_get_hw(parent);
+                       }
+
+                       if (!best_diff || tmp_rate < rate)
+                               break;
+               }
 
-       div = DIV_ROUND_CLOSEST(*parent_rate, rate);
-       if (div > SAM9X5_USB_MAX_DIV + 1)
-               div = SAM9X5_USB_MAX_DIV + 1;
+               if (!best_diff)
+                       break;
+       }
 
-       return DIV_ROUND_CLOSEST(*parent_rate, div);
+       return best_rate;
 }
 
 static int at91sam9x5_clk_usb_set_parent(struct clk_hw *hw, u8 index)
@@ -121,7 +154,7 @@ static int at91sam9x5_clk_usb_set_rate(struct clk_hw *hw, unsigned long rate,
 
 static const struct clk_ops at91sam9x5_usb_ops = {
        .recalc_rate = at91sam9x5_clk_usb_recalc_rate,
-       .round_rate = at91sam9x5_clk_usb_round_rate,
+       .determine_rate = at91sam9x5_clk_usb_determine_rate,
        .get_parent = at91sam9x5_clk_usb_get_parent,
        .set_parent = at91sam9x5_clk_usb_set_parent,
        .set_rate = at91sam9x5_clk_usb_set_rate,
@@ -159,7 +192,7 @@ static const struct clk_ops at91sam9n12_usb_ops = {
        .disable = at91sam9n12_clk_usb_disable,
        .is_enabled = at91sam9n12_clk_usb_is_enabled,
        .recalc_rate = at91sam9x5_clk_usb_recalc_rate,
-       .round_rate = at91sam9x5_clk_usb_round_rate,
+       .determine_rate = at91sam9x5_clk_usb_determine_rate,
        .set_rate = at91sam9x5_clk_usb_set_rate,
 };
 
@@ -179,7 +212,8 @@ at91sam9x5_clk_register_usb(struct at91_pmc *pmc, const char *name,
        init.ops = &at91sam9x5_usb_ops;
        init.parent_names = parent_names;
        init.num_parents = num_parents;
-       init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
+       init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE |
+                    CLK_SET_RATE_PARENT;
 
        usb->hw.init = &init;
        usb->pmc = pmc;
@@ -207,7 +241,7 @@ at91sam9n12_clk_register_usb(struct at91_pmc *pmc, const char *name,
        init.ops = &at91sam9n12_usb_ops;
        init.parent_names = &parent_name;
        init.num_parents = 1;
-       init.flags = CLK_SET_RATE_GATE;
+       init.flags = CLK_SET_RATE_GATE | CLK_SET_RATE_PARENT;
 
        usb->hw.init = &init;
        usb->pmc = pmc;