clk: renesas: rzg2l: Lock around writes to mux register

[ Upstream commit d2692ed490e680a41401cef879adebcfafb4298f ]

The SD MUX output (SD0) is further divided by 4 in G2{L,UL}.  The
divided clock is SD0_DIV4. SD0_DIV4 is registered with
CLK_SET_RATE_PARENT which means a rate request for it is propagated to
the MUX and could reach rzg2l_cpg_sd_clk_mux_set_parent() concurrently
with the users of SD0.
Add proper locking to avoid concurrent accesses on SD MUX set rate
registers.

Fixes: eaff33646f4cb ("clk: renesas: rzg2l: Add SDHI clk mux support")
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230929053915.1530607-4-claudiu.beznea@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/clk/renesas/rzg2l-cpg.c b/drivers/clk/renesas/rzg2l-cpg.c
index 9d25f7d..4c1f388 100644 (file)
--- a/drivers/clk/renesas/rzg2l-cpg.c
+++ b/drivers/clk/renesas/rzg2l-cpg.c
@@ -189,6 +189,7 @@ static int rzg2l_cpg_sd_clk_mux_set_parent(struct clk_hw *hw, u8 index)
        u32 shift = GET_SHIFT(hwdata->conf);
        const u32 clk_src_266 = 2;
        u32 msk, val, bitmask;
+       unsigned long flags;
        int ret;
 
        /*
@@ -204,23 +205,25 @@ static int rzg2l_cpg_sd_clk_mux_set_parent(struct clk_hw *hw, u8 index)
         */
        bitmask = (GENMASK(GET_WIDTH(hwdata->conf) - 1, 0) << shift) << 16;
        msk = off ? CPG_CLKSTATUS_SELSDHI1_STS : CPG_CLKSTATUS_SELSDHI0_STS;
+       spin_lock_irqsave(&priv->rmw_lock, flags);
        if (index != clk_src_266) {
                writel(bitmask | ((clk_src_266 + 1) << shift), priv->base + off);
 
-               ret = readl_poll_timeout(priv->base + CPG_CLKSTATUS, val,
-                                        !(val & msk), 100,
-                                        CPG_SDHI_CLK_SWITCH_STATUS_TIMEOUT_US);
-               if (ret) {
-                       dev_err(priv->dev, "failed to switch clk source\n");
-                       return ret;
-               }
+               ret = readl_poll_timeout_atomic(priv->base + CPG_CLKSTATUS, val,
+                                               !(val & msk), 10,
+                                               CPG_SDHI_CLK_SWITCH_STATUS_TIMEOUT_US);
+               if (ret)
+                       goto unlock;
        }
 
        writel(bitmask | ((index + 1) << shift), priv->base + off);
 
-       ret = readl_poll_timeout(priv->base + CPG_CLKSTATUS, val,
-                                !(val & msk), 100,
-                                CPG_SDHI_CLK_SWITCH_STATUS_TIMEOUT_US);
+       ret = readl_poll_timeout_atomic(priv->base + CPG_CLKSTATUS, val,
+                                       !(val & msk), 10,
+                                       CPG_SDHI_CLK_SWITCH_STATUS_TIMEOUT_US);
+unlock:
+       spin_unlock_irqrestore(&priv->rmw_lock, flags);
+
        if (ret)
                dev_err(priv->dev, "failed to switch clk source\n");
 

diff --git a/drivers/clk/renesas/rzg2l-cpg.h b/drivers/clk/renesas/rzg2l-cpg.h
index 6cee9e5..91e9c25 100644 (file)
--- a/drivers/clk/renesas/rzg2l-cpg.h
+++ b/drivers/clk/renesas/rzg2l-cpg.h
@@ -43,7 +43,7 @@
 #define CPG_CLKSTATUS_SELSDHI0_STS     BIT(28)
 #define CPG_CLKSTATUS_SELSDHI1_STS     BIT(29)
 
-#define CPG_SDHI_CLK_SWITCH_STATUS_TIMEOUT_US  20000
+#define CPG_SDHI_CLK_SWITCH_STATUS_TIMEOUT_US  200
 
 /* n = 0/1/2 for PLL1/4/6 */
 #define CPG_SAMPLL_CLK1(n)     (0x04 + (16 * n))