[PATCH v2 03/28] clk: renesas: rzg2l: lock around writes to mux register

Claudiu
2023-09-29T05:40:12Z

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

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 access 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>
---

Changes in v2:
- adapted delay_us to 10us
- adapted CPG_SDHI_CLK_SWITCH_STATUS_TIMEOUT_US to 200us; tested
with this adjustements on RZ/G3S and RZ/G2L SoCs

drivers/clk/renesas/rzg2l-cpg.c | 23 +++++++++++++----------
drivers/clk/renesas/rzg2l-cpg.h | 2 +-
2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/clk/renesas/rzg2l-cpg.c b/drivers/clk/renesas/rzg2l-cpg.c
index 5343d04fd70d..0679f2c7649e 100644
--- 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 0b28870a6f9d..097fd8f61680 100644
--- 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))
--
2.39.2