Re: [PATCH v5 2/4] mtd: rawnand: meson: fix the clock

[Neil Armstrong <narmstrong@baylibre.com>]

On 13/05/2022 14:34, Liang Yang wrote:
> EMMC and NAND have the same clock control register named 'SD_EMMC_CLOCK'
> which is defined in EMMC port internally. bit0~5 of 'SD_EMMC_CLOCK' is
> the divider and bit6~7 is the mux for fix pll and xtal. At the beginning,
> a common MMC and NAND sub-clock was discussed and planed to be implemented
> as NFC clock provider, but now this series of patches of a common MMC and
> NAND sub-clock are never being accepted.  the reasons for giving up are:
> 1. EMMC and NAND, which are mutually exclusive anyway
> 2. coupling the EMMC and NAND.
> 3. it seems that a common MMC and NAND sub-clock is over engineered.
> and let us see the link fot more information:
> https://lore.kernel.org/all/20220121074508.42168-5-liang.yang@amlogic.com
> so The meson nfc can't work now, let us rework the clock.
> 
> Signed-off-by: Liang Yang <liang.yang@amlogic.com>
> ---
>   drivers/mtd/nand/raw/meson_nand.c | 82 +++++++++++++++----------------
>   1 file changed, 41 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> index ac3be92872d0..cc93667a1e7f 100644
> --- a/drivers/mtd/nand/raw/meson_nand.c
> +++ b/drivers/mtd/nand/raw/meson_nand.c
> @@ -10,6 +10,7 @@
>   #include <linux/dma-mapping.h>
>   #include <linux/interrupt.h>
>   #include <linux/clk.h>
> +#include <linux/clk-provider.h>
>   #include <linux/mtd/rawnand.h>
>   #include <linux/mtd/mtd.h>
>   #include <linux/mfd/syscon.h>
> @@ -56,6 +57,9 @@
>   
>   #define NFC_RB_IRQ_EN		BIT(21)
>   
> +#define CLK_DIV_SHIFT		0
> +#define CLK_DIV_WIDTH		6
> +
>   #define CMDRWGEN(cmd_dir, ran, bch, short_mode, page_size, pages)	\
>   	(								\
>   		(cmd_dir)			|			\
> @@ -151,15 +155,15 @@ struct meson_nfc {
>   	struct nand_controller controller;
>   	struct clk *core_clk;
>   	struct clk *device_clk;
> -	struct clk *phase_tx;
> -	struct clk *phase_rx;
> +	struct clk *nand_clk;
> +	struct clk_divider nand_divider;
>   
>   	unsigned long clk_rate;
>   	u32 bus_timing;
>   
>   	struct device *dev;
>   	void __iomem *reg_base;
> -	struct regmap *reg_clk;
> +	void __iomem *reg_clk;
>   	struct completion completion;
>   	struct list_head chips;
>   	const struct meson_nfc_data *data;
> @@ -235,7 +239,7 @@ static void meson_nfc_select_chip(struct nand_chip *nand, int chip)
>   	nfc->timing.tbers_max = meson_chip->tbers_max;
>   
>   	if (nfc->clk_rate != meson_chip->clk_rate) {
> -		ret = clk_set_rate(nfc->device_clk, meson_chip->clk_rate);
> +		ret = clk_set_rate(nfc->nand_clk, meson_chip->clk_rate);
>   		if (ret) {
>   			dev_err(nfc->dev, "failed to set clock rate\n");
>   			return;
> @@ -987,6 +991,8 @@ static const struct mtd_ooblayout_ops meson_ooblayout_ops = {
>   
>   static int meson_nfc_clk_init(struct meson_nfc *nfc)
>   {
> +	struct clk_parent_data nfc_divider_parent_data[1];
> +	struct clk_init_data init = {0};
>   	int ret;
>   
>   	/* request core clock */
> @@ -1002,21 +1008,28 @@ static int meson_nfc_clk_init(struct meson_nfc *nfc)
>   		return PTR_ERR(nfc->device_clk);
>   	}
>   
> -	nfc->phase_tx = devm_clk_get(nfc->dev, "tx");
> -	if (IS_ERR(nfc->phase_tx)) {
> -		dev_err(nfc->dev, "failed to get TX clk\n");
> -		return PTR_ERR(nfc->phase_tx);
> -	}
> -
> -	nfc->phase_rx = devm_clk_get(nfc->dev, "rx");
> -	if (IS_ERR(nfc->phase_rx)) {
> -		dev_err(nfc->dev, "failed to get RX clk\n");
> -		return PTR_ERR(nfc->phase_rx);
> -	}
> +	init.name = devm_kasprintf(nfc->dev,
> +				   GFP_KERNEL, "%s#div",
> +				   dev_name(nfc->dev));
> +	init.ops = &clk_divider_ops;
> +	nfc_divider_parent_data[0].fw_name = "device";
> +	init.parent_data = nfc_divider_parent_data;
> +	init.num_parents = 1;
> +	nfc->nand_divider.reg = nfc->reg_clk;
> +	nfc->nand_divider.shift = CLK_DIV_SHIFT;
> +	nfc->nand_divider.width = CLK_DIV_WIDTH;
> +	nfc->nand_divider.hw.init = &init;
> +	nfc->nand_divider.flags = CLK_DIVIDER_ONE_BASED |
> +				  CLK_DIVIDER_ROUND_CLOSEST |
> +				  CLK_DIVIDER_ALLOW_ZERO;
> +
> +	nfc->nand_clk = devm_clk_register(nfc->dev, &nfc->nand_divider.hw);
> +	if (IS_ERR(nfc->nand_clk))
> +		return PTR_ERR(nfc->nand_clk);
>   
>   	/* init SD_EMMC_CLOCK to sane defaults w/min clock rate */
> -	regmap_update_bits(nfc->reg_clk,
> -			   0, CLK_SELECT_NAND, CLK_SELECT_NAND);
> +	writel(CLK_SELECT_NAND | readl(nfc->reg_clk),
> +	       nfc->reg_clk);
>   
>   	ret = clk_prepare_enable(nfc->core_clk);
>   	if (ret) {
> @@ -1030,29 +1043,21 @@ static int meson_nfc_clk_init(struct meson_nfc *nfc)
>   		goto err_device_clk;
>   	}
>   
> -	ret = clk_prepare_enable(nfc->phase_tx);
> +	ret = clk_prepare_enable(nfc->nand_clk);
>   	if (ret) {
> -		dev_err(nfc->dev, "failed to enable TX clock\n");
> -		goto err_phase_tx;
> +		dev_err(nfc->dev, "pre enable NFC divider fail\n");
> +		goto err_nand_clk;
>   	}
>   
> -	ret = clk_prepare_enable(nfc->phase_rx);
> -	if (ret) {
> -		dev_err(nfc->dev, "failed to enable RX clock\n");
> -		goto err_phase_rx;
> -	}
> -
> -	ret = clk_set_rate(nfc->device_clk, 24000000);
> +	ret = clk_set_rate(nfc->nand_clk, 24000000);
>   	if (ret)
> -		goto err_disable_rx;
> +		goto err_disable_clk;
>   
>   	return 0;
>   
> -err_disable_rx:
> -	clk_disable_unprepare(nfc->phase_rx);
> -err_phase_rx:
> -	clk_disable_unprepare(nfc->phase_tx);
> -err_phase_tx:
> +err_disable_clk:
> +	clk_disable_unprepare(nfc->nand_clk);
> +err_nand_clk:
>   	clk_disable_unprepare(nfc->device_clk);
>   err_device_clk:
>   	clk_disable_unprepare(nfc->core_clk);
> @@ -1061,8 +1066,7 @@ static int meson_nfc_clk_init(struct meson_nfc *nfc)
>   
>   static void meson_nfc_disable_clk(struct meson_nfc *nfc)
>   {
> -	clk_disable_unprepare(nfc->phase_rx);
> -	clk_disable_unprepare(nfc->phase_tx);
> +	clk_disable_unprepare(nfc->nand_clk);
>   	clk_disable_unprepare(nfc->device_clk);
>   	clk_disable_unprepare(nfc->core_clk);
>   }
> @@ -1396,13 +1400,9 @@ static int meson_nfc_probe(struct platform_device *pdev)
>   	if (IS_ERR(nfc->reg_base))
>   		return PTR_ERR(nfc->reg_base);
>   
> -	nfc->reg_clk =
> -		syscon_regmap_lookup_by_phandle(dev->of_node,
> -						"amlogic,mmc-syscon");
> -	if (IS_ERR(nfc->reg_clk)) {
> -		dev_err(dev, "Failed to lookup clock base\n");
> +	nfc->reg_clk = devm_platform_ioremap_resource_byname(pdev, "emmc");
> +	if (IS_ERR(nfc->reg_clk))
>   		return PTR_ERR(nfc->reg_clk);
> -	}
>   
>   	irq = platform_get_irq(pdev, 0);
>   	if (irq < 0)

Looks fine for me, thank for the changes:

Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

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