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Message-ID: <ace939d3-e57d-37ed-76e5-5a73233b881f@amlogic.com>
Date:   Mon, 11 Apr 2022 17:03:59 +0800
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Subject: Re: [PATCH v4 1/2] mtd: rawnand: meson: discard the common MMC sub
 clock framework
Content-Language: en-US
To:     Miquel Raynal <miquel.raynal@bootlin.com>
CC:     <linux-mtd@lists.infradead.org>, Rob Herring <robh+dt@kernel.org>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Kevin Hilman <khilman@baylibre.com>,
        Jianxin Pan <jianxin.pan@amlogic.com>,
        Victor Wan <victor.wan@amlogic.com>,
        XianWei Zhao <xianwei.zhao@amlogic.com>,
        Kelvin Zhang <kelvin.zhang@amlogic.com>,
        BiChao Zheng <bichao.zheng@amlogic.com>,
        YongHui Yu <yonghui.yu@amlogic.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-amlogic@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>
References: <20220402074921.13316-1-liang.yang@amlogic.com>
 <20220402074921.13316-2-liang.yang@amlogic.com>
 <20220404103034.48ec16b1@xps13>
 <50105d6b-8ced-1b72-30cb-a709c4a4dd26@amlogic.com>
 <20220411090015.6290b0b0@xps13>
From:   Liang Yang <liang.yang@amlogic.com>
In-Reply-To: <20220411090015.6290b0b0@xps13>
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Hi Miquel,


On 2022/4/11 15:00, Miquel Raynal wrote:
> [ EXTERNAL EMAIL ]
> 
> Hi Liang,
> 
> liang.yang@amlogic.com wrote on Mon, 11 Apr 2022 10:40:15 +0800:
> 
>> Hi Miquel,
>>
>> On 2022/4/4 16:30, Miquel Raynal wrote:
>>> [ EXTERNAL EMAIL ]
>>>
>>> Hi Liang,
>>>
>>> liang.yang@amlogic.com wrote on Sat, 2 Apr 2022 15:49:19 +0800:
>>>    
>>>> 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.A common MMC and NAND sub-clock has been
>>>> implemented and can be used by the eMMC and NAND controller (which are mutually
>>>> exclusive anyway). Let's use this new clock.
>>>>
>>>> Signed-off-by: Liang Yang <liang.yang@amlogic.com>
>>>> ---
>>>>    drivers/mtd/nand/raw/meson_nand.c | 89 +++++++++++++++----------------
>>>>    1 file changed, 42 insertions(+), 47 deletions(-)
>>>>
>>>> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
>>>> index ac3be92872d0..1b1a9407fb2f 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>
>>>> @@ -19,6 +20,7 @@
>>>>    #include <linux/iopoll.h>
>>>>    #include <linux/of.h>
>>>>    #include <linux/of_device.h>
>>>> +#include <linux/of_address.h>
>>>>    #include <linux/sched/task_stack.h>
>>>>    >>   #define NFC_REG_CMD		0x00
>>>> @@ -104,6 +106,9 @@
>>>>    >>   #define PER_INFO_BYTE		8
>>>>    >> +#define CLK_DIV_SHIFT		0
>>>> +#define CLK_DIV_WIDTH		6
>>>> +
>>>>    struct meson_nfc_nand_chip {
>>>>    	struct list_head node;
>>>>    	struct nand_chip nand;
>>>> @@ -151,15 +156,15 @@ 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 *sd_emmc_clock;
>>>>    	struct completion completion;
>>>>    	struct list_head chips;
>>>>    	const struct meson_nfc_data *data;
>>>> @@ -235,7 +240,7 @@ 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;
>>>> @@ -406,7 +411,6 @@ static int meson_nfc_queue_rb(struct meson_nfc *nfc, int timeout_ms)
>>>>    	cmd = NFC_CMD_RB | NFC_CMD_RB_INT
>>>>    		| nfc->param.chip_select | nfc->timing.tbers_max;
>>>>    	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>>>> -
>>>
>>> Please avoid these spacing changes in the middle of a commit.
>>
>> ok, i will fix it.
>>>    
>>>>    	ret = wait_for_completion_timeout(&nfc->completion,
>>>>    					  msecs_to_jiffies(timeout_ms));
>>>>    	if (ret == 0)
>>>> @@ -985,9 +989,11 @@ static const struct mtd_ooblayout_ops meson_ooblayout_ops = {
>>>>    	.free = meson_ooblayout_free,
>>>>    };
>>>>    >> +struct clk_parent_data nfc_divider_parent_data[1];
>>>>    static int meson_nfc_clk_init(struct meson_nfc *nfc)
>>>>    {
>>>>    	int ret;
>>>> +	struct clk_init_data init = {0};
>>>>    >>   	/* request core clock */
>>>>    	nfc->core_clk = devm_clk_get(nfc->dev, "core");
>>>> @@ -1002,21 +1008,26 @@ 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_kstrdup(nfc->dev, "nfc#div", GFP_KERNEL);
>>>> +	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->sd_emmc_clock;
>>>> +	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->sd_emmc_clock),
>>>> +	       nfc->sd_emmc_clock);
>>>>    >>   	ret = clk_prepare_enable(nfc->core_clk);
>>>>    	if (ret) {
>>>> @@ -1030,29 +1041,21 @@ 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);
>>>
>>> Is this rename really useful?
>>
>> yes, it works.
> 
> I understand it works, but if this is just a name change of a variable
> in your driver that has implications everywhere in this driver, then
> it's probably best to do it in a separate commit to ease the review.
> After apply these patches, i think we have to change the clk from 
device_clk to nand_clk. previously the device_clk comes from 
<&sd_emmc_c_clkc CLKID_MMC_DIV> in dts and we set device_clk to give NFC 
controller the clock; now device_clk comes from <&clkc CLKID_FCLK_DIV2> 
which is the parent node of nand_clk, so we set nand_clk to give NFC 
controller the clock.

>>
>>>    
>>>>    	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 +1064,7 @@ 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);
>>>>    }
>>>> @@ -1374,7 +1376,6 @@ static int meson_nfc_probe(struct platform_device *pdev)
>>>>    {
>>>>    	struct device *dev = &pdev->dev;
>>>>    	struct meson_nfc *nfc;
>>>> -	struct resource *res;
>>>>    	int ret, irq;
>>>>    >>   	nfc = devm_kzalloc(dev, sizeof(*nfc), GFP_KERNEL);
>>>> @@ -1388,21 +1389,15 @@ static int meson_nfc_probe(struct platform_device *pdev)
>>>>    	nand_controller_init(&nfc->controller);
>>>>    	INIT_LIST_HEAD(&nfc->chips);
>>>>    	init_completion(&nfc->completion);
>>>> -
>>>
>>> Please don't modify spacing in this commit.
>>> ok
>>
>>>>    	nfc->dev = dev;
>>>>    >> -	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>> -	nfc->reg_base = devm_ioremap_resource(dev, res);
>>>> +	nfc->reg_base = devm_platform_ioremap_resource_byname(pdev, "nfc");
>>>
>>> This change seems unrelated.
>>
>> To be consistent with the following devm_platform_ioremap_resource_byname(pdev, "emmc"). do you mean that we don't need it?>
> 
> So indeed it should not be in this commit. You can do that as a
> preparation patch if you wish.

ok. May i split this change as one of patches in this series?

> 
>>>>    	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");
>>>> -		return PTR_ERR(nfc->reg_clk);
>>>> -	}
>>>> +	nfc->sd_emmc_clock = devm_platform_ioremap_resource_byname(pdev, "emmc");
>>>> +	if (IS_ERR(nfc->sd_emmc_clock))
>>>> +		return PTR_ERR(nfc->sd_emmc_clock);
>>>
>>> While I agree this is much better than the previous solution, we cannot
>>> break DT compatibility, so you need to try getting the emmc clock, but
>>> if it fails you should fallback to the regmap lookup.
>>
>> ok, i will fix it next version. thanks.
>>
>>>    
>>>>    >>   	irq = platform_get_irq(pdev, 0);
>>>>    	if (irq < 0)
>>>
>>>
>>> Thanks,
>>> Miquèl
>>>
>>> .
> 
> 
> Thanks,
> Miquèl
> 
> .