clk: pistachio: Add sanity checks on PLL configuration

When setting the PLL rates, check that:

 - VCO is within range
 - PFD is within range
 - PLL is disabled when postdiv is changed
 - postdiv2 <= postdiv1

Reviewed-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

diff --git a/drivers/clk/pistachio/clk-pll.c b/drivers/clk/pistachio/clk-pll.c
index f12d520..e17dada 100644 (file)
--- a/drivers/clk/pistachio/clk-pll.c
+++ b/drivers/clk/pistachio/clk-pll.c
@@ -6,9 +6,12 @@
  * version 2, as published by the Free Software Foundation.
  */
 
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
 #include <linux/clk-provider.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/printk.h>
 #include <linux/slab.h>
 
 #include "clk.h"
@@ -50,6 +53,18 @@
 #define PLL_CTRL4                      0x10
 #define PLL_FRAC_CTRL4_BYPASS          BIT(28)
 
+#define MIN_PFD                                9600000UL
+#define MIN_VCO_LA                     400000000UL
+#define MAX_VCO_LA                     1600000000UL
+#define MIN_VCO_FRAC_INT               600000000UL
+#define MAX_VCO_FRAC_INT               1600000000UL
+#define MIN_VCO_FRAC_FRAC              600000000UL
+#define MAX_VCO_FRAC_FRAC              2400000000UL
+#define MIN_OUTPUT_LA                  8000000UL
+#define MAX_OUTPUT_LA                  1600000000UL
+#define MIN_OUTPUT_FRAC                        12000000UL
+#define MAX_OUTPUT_FRAC                        1600000000UL
+
 struct pistachio_clk_pll {
        struct clk_hw hw;
        void __iomem *base;
@@ -158,12 +173,29 @@ static int pll_gf40lp_frac_set_rate(struct clk_hw *hw, unsigned long rate,
        struct pistachio_clk_pll *pll = to_pistachio_pll(hw);
        struct pistachio_pll_rate_table *params;
        int enabled = pll_gf40lp_frac_is_enabled(hw);
-       u32 val;
+       u32 val, vco, old_postdiv1, old_postdiv2;
+       const char *name = __clk_get_name(hw->clk);
+
+       if (rate < MIN_OUTPUT_FRAC || rate > MAX_OUTPUT_FRAC)
+               return -EINVAL;
 
        params = pll_get_params(pll, parent_rate, rate);
-       if (!params)
+       if (!params || !params->refdiv)
                return -EINVAL;
 
+       vco = params->fref * params->fbdiv / params->refdiv;
+       if (vco < MIN_VCO_FRAC_FRAC || vco > MAX_VCO_FRAC_FRAC)
+               pr_warn("%s: VCO %u is out of range %lu..%lu\n", name, vco,
+                       MIN_VCO_FRAC_FRAC, MAX_VCO_FRAC_FRAC);
+
+       val = params->fref / params->refdiv;
+       if (val < MIN_PFD)
+               pr_warn("%s: PFD %u is too low (min %lu)\n",
+                       name, val, MIN_PFD);
+       if (val > vco / 16)
+               pr_warn("%s: PFD %u is too high (max %u)\n",
+                       name, val, vco / 16);
+
        val = pll_readl(pll, PLL_CTRL1);
        val &= ~((PLL_CTRL1_REFDIV_MASK << PLL_CTRL1_REFDIV_SHIFT) |
                 (PLL_CTRL1_FBDIV_MASK << PLL_CTRL1_FBDIV_SHIFT));
@@ -172,6 +204,19 @@ static int pll_gf40lp_frac_set_rate(struct clk_hw *hw, unsigned long rate,
        pll_writel(pll, val, PLL_CTRL1);
 
        val = pll_readl(pll, PLL_CTRL2);
+
+       old_postdiv1 = (val >> PLL_FRAC_CTRL2_POSTDIV1_SHIFT) &
+                      PLL_FRAC_CTRL2_POSTDIV1_MASK;
+       old_postdiv2 = (val >> PLL_FRAC_CTRL2_POSTDIV2_SHIFT) &
+                      PLL_FRAC_CTRL2_POSTDIV2_MASK;
+       if (enabled &&
+           (params->postdiv1 != old_postdiv1 ||
+            params->postdiv2 != old_postdiv2))
+               pr_warn("%s: changing postdiv while PLL is enabled\n", name);
+
+       if (params->postdiv2 > params->postdiv1)
+               pr_warn("%s: postdiv2 should not exceed postdiv1\n", name);
+
        val &= ~((PLL_FRAC_CTRL2_FRAC_MASK << PLL_FRAC_CTRL2_FRAC_SHIFT) |
                 (PLL_FRAC_CTRL2_POSTDIV1_MASK <<
                  PLL_FRAC_CTRL2_POSTDIV1_SHIFT) |
@@ -270,13 +315,43 @@ static int pll_gf40lp_laint_set_rate(struct clk_hw *hw, unsigned long rate,
        struct pistachio_clk_pll *pll = to_pistachio_pll(hw);
        struct pistachio_pll_rate_table *params;
        int enabled = pll_gf40lp_laint_is_enabled(hw);
-       u32 val;
+       u32 val, vco, old_postdiv1, old_postdiv2;
+       const char *name = __clk_get_name(hw->clk);
+
+       if (rate < MIN_OUTPUT_LA || rate > MAX_OUTPUT_LA)
+               return -EINVAL;
 
        params = pll_get_params(pll, parent_rate, rate);
-       if (!params)
+       if (!params || !params->refdiv)
                return -EINVAL;
 
+       vco = params->fref * params->fbdiv / params->refdiv;
+       if (vco < MIN_VCO_LA || vco > MAX_VCO_LA)
+               pr_warn("%s: VCO %u is out of range %lu..%lu\n", name, vco,
+                       MIN_VCO_LA, MAX_VCO_LA);
+
+       val = params->fref / params->refdiv;
+       if (val < MIN_PFD)
+               pr_warn("%s: PFD %u is too low (min %lu)\n",
+                       name, val, MIN_PFD);
+       if (val > vco / 16)
+               pr_warn("%s: PFD %u is too high (max %u)\n",
+                       name, val, vco / 16);
+
        val = pll_readl(pll, PLL_CTRL1);
+
+       old_postdiv1 = (val >> PLL_INT_CTRL1_POSTDIV1_SHIFT) &
+                      PLL_INT_CTRL1_POSTDIV1_MASK;
+       old_postdiv2 = (val >> PLL_INT_CTRL1_POSTDIV2_SHIFT) &
+                      PLL_INT_CTRL1_POSTDIV2_MASK;
+       if (enabled &&
+           (params->postdiv1 != old_postdiv1 ||
+            params->postdiv2 != old_postdiv2))
+               pr_warn("%s: changing postdiv while PLL is enabled\n", name);
+
+       if (params->postdiv2 > params->postdiv1)
+               pr_warn("%s: postdiv2 should not exceed postdiv1\n", name);
+
        val &= ~((PLL_CTRL1_REFDIV_MASK << PLL_CTRL1_REFDIV_SHIFT) |
                 (PLL_CTRL1_FBDIV_MASK << PLL_CTRL1_FBDIV_SHIFT) |
                 (PLL_INT_CTRL1_POSTDIV1_MASK << PLL_INT_CTRL1_POSTDIV1_SHIFT) |