linux-kernel - [PATCH 4.7 148/184] mmc: sdhci-st: Handle interconnect clock

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Date:   Thu, 22 Sep 2016 19:41:22 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Peter Griffin <peter.griffin@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: [PATCH 4.7 148/184] mmc: sdhci-st: Handle interconnect clock

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lee Jones <lee.jones@...aro.org>

commit 3ae50f4512ce831e8b63eb54ad969417ff30ada7 upstream.

Some ST platforms contain interconnect (ICN) clocks which must be handed
correctly in order to obtain full functionality of a given IP.  In this
case, if the ICN clocks are not handled properly by the ST SDHCI driver
MMC will break and the following output can be observed:

    [   13.916949] mmc0: Timeout waiting for hardware interrupt.
    [   13.922349] sdhci: =========== REGISTER DUMP (mmc0)===========
    [   13.928175] sdhci: Sys addr: 0x00000000 | Version:  0x00001002
    [   13.933999] sdhci: Blk size: 0x00007040 | Blk cnt:  0x00000001
    [   13.939825] sdhci: Argument: 0x00fffff0 | Trn mode: 0x00000013
    [   13.945650] sdhci: Present:  0x1fff0206 | Host ctl: 0x00000011
    [   13.951475] sdhci: Power:    0x0000000f | Blk gap:  0x00000080
    [   13.957300] sdhci: Wake-up:  0x00000000 | Clock:    0x00003f07
    [   13.963126] sdhci: Timeout:  0x00000004 | Int stat: 0x00000000
    [   13.968952] sdhci: Int enab: 0x02ff008b | Sig enab: 0x02ff008b
    [   13.974777] sdhci: AC12 err: 0x00000000 | Slot int: 0x00000000
    [   13.980602] sdhci: Caps:     0x21ed3281 | Caps_1:   0x00000000
    [   13.986428] sdhci: Cmd:      0x0000063a | Max curr: 0x00000000
    [   13.992252] sdhci: Host ctl2: 0x00000000
    [   13.996166] sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x7c048200
    [   14.001990] sdhci: ===========================================
    [   14.009802] mmc0: Got data interrupt 0x02000000 even though no data operation was in progress.

A decent point was raised about minimising the use of a local variable that
we 'could' do without.  I've chosen consistency over the possibility of
reducing the local variable count by 1.  Thinking that it's more important
for the code to be grouped and authoured in a similar manner/style for
greater maintainability/readability.

Tested-by: Peter Griffin <peter.griffin@...aro.org>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/mmc/host/sdhci-st.c |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

--- a/drivers/mmc/host/sdhci-st.c
+++ b/drivers/mmc/host/sdhci-st.c
@@ -28,6 +28,7 @@
 
 struct st_mmc_platform_data {
 	struct  reset_control *rstc;
+	struct  clk *icnclk;
 	void __iomem *top_ioaddr;
 };
 
@@ -353,7 +354,7 @@ static int sdhci_st_probe(struct platfor
 	struct sdhci_host *host;
 	struct st_mmc_platform_data *pdata;
 	struct sdhci_pltfm_host *pltfm_host;
-	struct clk *clk;
+	struct clk *clk, *icnclk;
 	int ret = 0;
 	u16 host_version;
 	struct resource *res;
@@ -365,6 +366,11 @@ static int sdhci_st_probe(struct platfor
 		return PTR_ERR(clk);
 	}
 
+	/* ICN clock isn't compulsory, but use it if it's provided. */
+	icnclk = devm_clk_get(&pdev->dev, "icn");
+	if (IS_ERR(icnclk))
+		icnclk = NULL;
+
 	rstc = devm_reset_control_get(&pdev->dev, NULL);
 	if (IS_ERR(rstc))
 		rstc = NULL;
@@ -389,6 +395,7 @@ static int sdhci_st_probe(struct platfor
 	}
 
 	clk_prepare_enable(clk);
+	clk_prepare_enable(icnclk);
 
 	/* Configure the FlashSS Top registers for setting eMMC TX/RX delay */
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
@@ -400,6 +407,7 @@ static int sdhci_st_probe(struct platfor
 	}
 
 	pltfm_host->clk = clk;
+	pdata->icnclk = icnclk;
 
 	/* Configure the Arasan HC inside the flashSS */
 	st_mmcss_cconfig(np, host);
@@ -422,6 +430,7 @@ static int sdhci_st_probe(struct platfor
 	return 0;
 
 err_out:
+	clk_disable_unprepare(icnclk);
 	clk_disable_unprepare(clk);
 err_of:
 	sdhci_pltfm_free(pdev);
@@ -442,6 +451,8 @@ static int sdhci_st_remove(struct platfo
 
 	ret = sdhci_pltfm_unregister(pdev);
 
+	clk_disable_unprepare(pdata->icnclk);
+
 	if (rstc)
 		reset_control_assert(rstc);
 
@@ -462,6 +473,7 @@ static int sdhci_st_suspend(struct devic
 	if (pdata->rstc)
 		reset_control_assert(pdata->rstc);
 
+	clk_disable_unprepare(pdata->icnclk);
 	clk_disable_unprepare(pltfm_host->clk);
 out:
 	return ret;
@@ -475,6 +487,7 @@ static int sdhci_st_resume(struct device
 	struct device_node *np = dev->of_node;
 
 	clk_prepare_enable(pltfm_host->clk);
+	clk_prepare_enable(pdata->icnclk);
 
 	if (pdata->rstc)
 		reset_control_deassert(pdata->rstc);