clk: qcom: clk-krait: add apq/ipq8064 errata workaround

Add apq/ipq8064 errata workaround where the sec_src clock gating needs to
be disabled during switching. krait-cc compatible is not enough to
handle this and limit this workaround to apq/ipq8064. We check machine
compatible to handle this.

Signed-off-by: Ansuel Smith <[e-mail]>
Reviewed-by: Dmitry Baryshkov <[e-mail]>
Signed-off-by: Bjorn Andersson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/clk/qcom/clk-krait.c

···
 static DEFINE_SPINLOCK(krait_clock_reg_lock);
 
 #define LPL_SHIFT	8
+#define SECCLKAGD	BIT(4)
+
 static void __krait_mux_set_sel(struct krait_mux_clk *mux, int sel)
 {
 	unsigned long flags;
 	u32 regval;
 
 	spin_lock_irqsave(&krait_clock_reg_lock, flags);
+
 	regval = krait_get_l2_indirect_reg(mux->offset);
+
+	/* apq/ipq8064 Errata: disable sec_src clock gating during switch. */
+	if (mux->disable_sec_src_gating) {
+		regval |= SECCLKAGD;
+		krait_set_l2_indirect_reg(mux->offset, regval);
+	}
+
 	regval &= ~(mux->mask << mux->shift);
 	regval |= (sel & mux->mask) << mux->shift;
 	if (mux->lpl) {
···
 		regval |= (sel & mux->mask) << (mux->shift + LPL_SHIFT);
 	}
 	krait_set_l2_indirect_reg(mux->offset, regval);
+
+	/* apq/ipq8064 Errata: re-enabled sec_src clock gating. */
+	if (mux->disable_sec_src_gating) {
+		regval &= ~SECCLKAGD;
+		krait_set_l2_indirect_reg(mux->offset, regval);
+	}
 
 	/* Wait for switch to complete. */
 	mb();

drivers/clk/qcom/clk-krait.h

···
 	u8		safe_sel;
 	u8		old_index;
 	bool		reparent;
+	bool		disable_sec_src_gating;
 
 	struct clk_hw	hw;
 	struct notifier_block   clk_nb;

drivers/clk/qcom/krait-cc.c

···
 	mux->hw.init = &init;
 	mux->safe_sel = 0;
 
+	/* Checking for qcom,krait-cc-v1 or qcom,krait-cc-v2 is not
+	 * enough to limit this to apq/ipq8064. Directly check machine
+	 * compatible to correctly handle this errata.
+	 */
+	if (of_machine_is_compatible("qcom,ipq8064") ||
+	    of_machine_is_compatible("qcom,apq8064"))
+		mux->disable_sec_src_gating = true;
+
 	init.name = kasprintf(GFP_KERNEL, "krait%s_sec_mux", s);
 	if (!init.name)
 		return -ENOMEM;