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    Subject[PATCH 3/3] nvmem: imx-ocotp: handling clock
    Date
    Before access ocotp nvmem area, the clock should be enabled.
    Or, `hexdump nvmem` will hang the system. So, use such flow:
    "
    1. clock_enable_prepare
    2. read nvmem ocotp area
    3. clock_disable_unprepare
    "

    Signed-off-by: Peng Fan <van.freenix@gmail.com>
    Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
    Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
    Cc: Shawn Guo <shawnguo@kernel.org>
    ---
    drivers/nvmem/imx-ocotp.c | 10 ++++++++++
    1 file changed, 10 insertions(+)

    diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c
    index d7796eb..55095c0 100644
    --- a/drivers/nvmem/imx-ocotp.c
    +++ b/drivers/nvmem/imx-ocotp.c
    @@ -15,6 +15,7 @@
    * http://www.gnu.org/copyleft/gpl.html
    */

    +#include <linux/clk.h>
    #include <linux/device.h>
    #include <linux/io.h>
    #include <linux/module.h>
    @@ -27,6 +28,7 @@

    struct ocotp_priv {
    struct device *dev;
    + struct clk *clk;
    void __iomem *base;
    unsigned int nregs;
    };
    @@ -46,11 +48,15 @@ static int imx_ocotp_read(void *context, const void *reg, size_t reg_size,
    if (count > (priv->nregs - index))
    count = priv->nregs - index;

    + clk_prepare_enable(priv->clk);
    +
    for (i = index; i < (index + count); i++) {
    *(u32 *)val = readl(priv->base + 0x400 + i * 0x10);
    val += 4;
    }

    + clk_disable_unprepare(priv->clk);
    +
    return 0;
    }

    @@ -112,6 +118,10 @@ static int imx_ocotp_probe(struct platform_device *pdev)
    if (IS_ERR(priv->base))
    return PTR_ERR(priv->base);

    + priv->clk = devm_clk_get(&pdev->dev, NULL);
    + if (IS_ERR(priv->clk))
    + return PTR_ERR(priv->clk);
    +
    of_id = of_match_device(imx_ocotp_dt_ids, dev);
    priv->nregs = (unsigned int)of_id->data;
    imx_ocotp_regmap_config.max_register = 4 * priv->nregs - 4;
    --
    1.8.4.5
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