clk: ti: omap5+: dpll: implement errata i810

Errata i810 states that DPLL controller can get stuck while transitioning
to a power saving state, while its M/N ratio is being re-programmed.

As a workaround, before re-programming the M/N ratio, SW has to ensure
the DPLL cannot start an idle state transition. SW can disable DPLL
idling by setting the DPLL AUTO_DPLL_MODE=0 or keeping a clock request
active by setting a dependent clock domain in SW_WKUP.

This errata impacts OMAP5 and DRA7 chips, so enable the errata for these.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

3 files changed, 29 insertions, 1 deletions

diff --git a/arch/arm/mach-omap2/clock.c b/arch/arm/mach-omap2/clock.c
index acb60ed17273..d058125876d8 100644
--- a/arch/arm/mach-omap2/clock.c
+++ b/arch/arm/mach-omap2/clock.c
@@ -225,5 +225,9 @@ void __init ti_clk_init_features(void)
         if (omap_rev() == OMAP3430_REV_ES1_0)
                 features.flags |= TI_CLK_DPLL4_DENY_REPROGRAM;
 
+        /* Errata I810 for omap5 / dra7 */
+        if (soc_is_omap54xx() || soc_is_dra7xx())
+                features.flags |= TI_CLK_ERRATA_I810;
+
         ti_clk_setup_features(&features);
 }
diff --git a/drivers/clk/ti/dpll3xxx.c b/drivers/clk/ti/dpll3xxx.c
index f4dec00fb684..1c300388782b 100644
--- a/drivers/clk/ti/dpll3xxx.c
+++ b/drivers/clk/ti/dpll3xxx.c
@@ -305,8 +305,9 @@ static void _lookup_sddiv(struct clk_hw_omap *clk, u8 *sd_div, u16 m, u8 n)
 static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel)
 {
         struct dpll_data *dd = clk->dpll_data;
-        u8 dco, sd_div;
+        u8 dco, sd_div, ai = 0;
         u32 v;
+        bool errata_i810;
 
         /* 3430 ES2 TRM: 4.7.6.9 DPLL Programming Sequence */
         _omap3_noncore_dpll_bypass(clk);
@@ -350,6 +351,25 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel)
                 v |= sd_div << __ffs(dd->sddiv_mask);
         }
 
+        /*
+         * Errata i810 - DPLL controller can get stuck while transitioning
+         * to a power saving state. Software must ensure the DPLL can not
+         * transition to a low power state while changing M/N values.
+         * Easiest way to accomplish this is to prevent DPLL autoidle
+         * before doing the M/N re-program.
+         */
+        errata_i810 = ti_clk_get_features()->flags & TI_CLK_ERRATA_I810;
+
+        if (errata_i810) {
+                ai = omap3_dpll_autoidle_read(clk);
+                if (ai) {
+                        omap3_dpll_deny_idle(clk);
+
+                        /* OCP barrier */
+                        omap3_dpll_autoidle_read(clk);
+                }
+        }
+
         ti_clk_ll_ops->clk_writel(v, dd->mult_div1_reg);
 
         /* Set 4X multiplier and low-power mode */
@@ -379,6 +399,9 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel)
 
         _omap3_noncore_dpll_lock(clk);
 
+        if (errata_i810 && ai)
+                omap3_dpll_allow_idle(clk);
+
         return 0;
 }
 
diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
index 223be696df27..75205df29b9c 100644
--- a/include/linux/clk/ti.h
+++ b/include/linux/clk/ti.h
@@ -286,6 +286,7 @@ struct ti_clk_features {
 #define TI_CLK_DPLL_HAS_FREQSEL                 BIT(0)
 #define TI_CLK_DPLL4_DENY_REPROGRAM             BIT(1)
 #define TI_CLK_DISABLE_CLKDM_CONTROL            BIT(2)
+#define TI_CLK_ERRATA_I810                      BIT(3)
 
 void ti_clk_setup_features(struct ti_clk_features *features);
 const struct ti_clk_features *ti_clk_get_features(void);