clk: qoriq: Don't allow CPU clocks higher than starting value

The boot-time frequency of a CPU is considered its rated maximum, as we
have no other source of such information.  However, this was previously
only used for chips with 80% restrictions on secondary PLLs.  This
usually wasn't a problem because most chips/configs boot with a divider
of /1, with other dividers being used only for dynamic frequency
reduction.  However, at least one config (LS1021A at less than 1 GHz)
uses a different divider for top speed.  This was causing cpufreq to set
a frequency beyond the chip's rated speed.

This is fixed by applying a 100%-of-initial-speed limit to all CPU PLLs,
similar to the existing 80% limit that only applied to some.

Signed-off-by: Scott Wood <oss@buserror.net>
Cc: stable@vger.kernel.org
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/clk/clk-qoriq.c b/drivers/clk/clk-qoriq.c
index 20b105584f82..80ae2a51452d 100644
--- a/drivers/clk/clk-qoriq.c
+++ b/drivers/clk/clk-qoriq.c
@@ -700,6 +700,7 @@ static struct clk * __init create_mux_common(struct clockgen *cg,
                                              struct mux_hwclock *hwc,
                                              const struct clk_ops *ops,
                                              unsigned long min_rate,
+                                             unsigned long max_rate,
                                              unsigned long pct80_rate,
                                              const char *fmt, int idx)
 {
@@ -728,6 +729,8 @@ static struct clk * __init create_mux_common(struct clockgen *cg,
                         continue;
                 if (rate < min_rate)
                         continue;
+                if (rate > max_rate)
+                        continue;
 
                 parent_names[j] = div->name;
                 hwc->parent_to_clksel[j] = i;
@@ -759,7 +762,7 @@ static struct clk * __init create_one_cmux(struct clockgen *cg, int idx)
         struct mux_hwclock *hwc;
         const struct clockgen_pll_div *div;
         unsigned long plat_rate, min_rate;
-        u64 pct80_rate;
+        u64 max_rate, pct80_rate;
         u32 clksel;
 
         hwc = kzalloc(sizeof(*hwc), GFP_KERNEL);
@@ -787,8 +790,8 @@ static struct clk * __init create_one_cmux(struct clockgen *cg, int idx)
                 return NULL;
         }
 
-        pct80_rate = clk_get_rate(div->clk);
-        pct80_rate *= 8;
+        max_rate = clk_get_rate(div->clk);
+        pct80_rate = max_rate * 8;
         do_div(pct80_rate, 10);
 
         plat_rate = clk_get_rate(cg->pll[PLATFORM_PLL].div[PLL_DIV1].clk);
@@ -798,7 +801,7 @@ static struct clk * __init create_one_cmux(struct clockgen *cg, int idx)
         else
                 min_rate = plat_rate / 2;
 
-        return create_mux_common(cg, hwc, &cmux_ops, min_rate,
+        return create_mux_common(cg, hwc, &cmux_ops, min_rate, max_rate,
                                  pct80_rate, "cg-cmux%d", idx);
 }
 
@@ -813,7 +816,7 @@ static struct clk * __init create_one_hwaccel(struct clockgen *cg, int idx)
         hwc->reg = cg->regs + 0x20 * idx + 0x10;
         hwc->info = cg->info.hwaccel[idx];
 
-        return create_mux_common(cg, hwc, &hwaccel_ops, 0, 0,
+        return create_mux_common(cg, hwc, &hwaccel_ops, 0, ULONG_MAX, 0,
                                  "cg-hwaccel%d", idx);
 }