[PATCH linux dev-5.4 1/2] clk: AST2600: Add mux for EMMC clock

[PATCH linux dev-5.4 1/2] clk: AST2600: Add mux for EMMC clock

[Eddie James]

The EMMC clock can be derived from either the HPLL or the MPLL. Register
a clock mux so that the rate is calculated correctly based upon the
parent.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 drivers/clk/clk-ast2600.c | 49 ++++++++++++++++++++++++++++++++-------
 1 file changed, 41 insertions(+), 8 deletions(-)

diff --git a/drivers/clk/clk-ast2600.c b/drivers/clk/clk-ast2600.c
index 35f53956c762..bbacaccad554 100644
--- a/drivers/clk/clk-ast2600.c
+++ b/drivers/clk/clk-ast2600.c
@@ -131,6 +131,18 @@ static const struct clk_div_table ast2600_eclk_div_table[] = {
 	{ 0 }
 };
 
+static const struct clk_div_table ast2600_emmc_extclk_div_table[] = {
+	{ 0x0, 2 },
+	{ 0x1, 4 },
+	{ 0x2, 6 },
+	{ 0x3, 8 },
+	{ 0x4, 10 },
+	{ 0x5, 12 },
+	{ 0x6, 14 },
+	{ 0x7, 16 },
+	{ 0 }
+};
+
 static const struct clk_div_table ast2600_mac_div_table[] = {
 	{ 0x0, 4 },
 	{ 0x1, 4 },
@@ -390,6 +402,11 @@ static struct clk_hw *aspeed_g6_clk_hw_register_gate(struct device *dev,
 	return hw;
 }
 
+static const char *const emmc_extclk_parent_names[] = {
+	"emmc_extclk_hpll_in",
+	"mpll",
+};
+
 static const char * const vclk_parent_names[] = {
 	"dpll",
 	"d1pll",
@@ -459,16 +476,32 @@ static int aspeed_g6_clk_probe(struct platform_device *pdev)
 		return PTR_ERR(hw);
 	aspeed_g6_clk_data->hws[ASPEED_CLK_UARTX] = hw;
 
-	/* EMMC ext clock divider */
-	hw = clk_hw_register_gate(dev, "emmc_extclk_gate", "hpll", 0,
-			scu_g6_base + ASPEED_G6_CLK_SELECTION1, 15, 0,
-			&aspeed_g6_clk_lock);
+	/* EMMC ext clock */
+	hw = clk_hw_register_fixed_factor(dev, "emmc_extclk_hpll_in", "hpll",
+					  0, 1, 2);
 	if (IS_ERR(hw))
 		return PTR_ERR(hw);
-	hw = clk_hw_register_divider_table(dev, "emmc_extclk", "emmc_extclk_gate", 0,
-			scu_g6_base + ASPEED_G6_CLK_SELECTION1, 12, 3, 0,
-			ast2600_div_table,
-			&aspeed_g6_clk_lock);
+
+	hw = clk_hw_register_mux(dev, "emmc_extclk_mux",
+				 emmc_extclk_parent_names,
+				 ARRAY_SIZE(emmc_extclk_parent_names), 0,
+				 scu_g6_base + ASPEED_G6_CLK_SELECTION1, 11, 1,
+				 0, &aspeed_g6_clk_lock);
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+
+	hw = clk_hw_register_gate(dev, "emmc_extclk_gate", "emmc_extclk_mux",
+				  0, scu_g6_base + ASPEED_G6_CLK_SELECTION1,
+				  15, 0, &aspeed_g6_clk_lock);
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+
+	hw = clk_hw_register_divider_table(dev, "emmc_extclk",
+					   "emmc_extclk_gate", 0,
+					   scu_g6_base +
+						ASPEED_G6_CLK_SELECTION1, 12,
+					   3, 0, ast2600_emmc_extclk_div_table,
+					   &aspeed_g6_clk_lock);
 	if (IS_ERR(hw))
 		return PTR_ERR(hw);
 	aspeed_g6_clk_data->hws[ASPEED_CLK_EMMC] = hw;
-- 
2.24.0

[PATCH linux dev-5.4 2/2] mmc: sdhci-of-aspeed: Prevent clock divider of zero

[Eddie James]

The Aspeed specification forbids a clock divider of zero, which will be
calculated if the parent clock is equal to the desired clock. Testing
confirmed this broke the host controller.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 drivers/mmc/host/sdhci-of-aspeed.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/mmc/host/sdhci-of-aspeed.c b/drivers/mmc/host/sdhci-of-aspeed.c
index 8962f6664381..5aa72e80cae9 100644
--- a/drivers/mmc/host/sdhci-of-aspeed.c
+++ b/drivers/mmc/host/sdhci-of-aspeed.c
@@ -74,6 +74,10 @@ static void aspeed_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
 	}
 	div >>= 1;
 
+	/* Aspeed forbids a clock div of 0 */
+	if (!div)
+		div = 1;
+
 	clk = div << SDHCI_DIVIDER_SHIFT;
 
 	sdhci_enable_clk(host, clk);
-- 
2.24.0

Re: [PATCH linux dev-5.4 2/2] mmc: sdhci-of-aspeed: Prevent clock divider of zero

[Andrew Jeffery]

On Thu, 9 Jul 2020, at 05:54, Eddie James wrote:
> The Aspeed specification forbids a clock divider of zero, which will be
> calculated if the parent clock is equal to the desired clock. Testing
> confirmed this broke the host controller.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> ---
>  drivers/mmc/host/sdhci-of-aspeed.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-aspeed.c 
> b/drivers/mmc/host/sdhci-of-aspeed.c
> index 8962f6664381..5aa72e80cae9 100644
> --- a/drivers/mmc/host/sdhci-of-aspeed.c
> +++ b/drivers/mmc/host/sdhci-of-aspeed.c
> @@ -74,6 +74,10 @@ static void aspeed_sdhci_set_clock(struct sdhci_host 
> *host, unsigned int clock)
>  	}
>  	div >>= 1;
>  
> +	/* Aspeed forbids a clock div of 0 */
> +	if (!div)
> +		div = 1;
> +

Nah, the search loop needs to initialise with div = 2. The current implementation is busted.

Re: [PATCH linux dev-5.4 1/2] clk: AST2600: Add mux for EMMC clock

[Andrew Jeffery]

On Thu, 9 Jul 2020, at 05:54, Eddie James wrote:
> The EMMC clock can be derived from either the HPLL or the MPLL. Register
> a clock mux so that the rate is calculated correctly based upon the
> parent.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>

Reviewed-by: Andrew Jeffery <andrew@aj.id.au>