linux-kernel - Re: [PATCH v2 1/3] spi: meson-axg: support MAX 80M clock

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Message-ID: <2d438907-91b5-7443-24f9-57a406aaa040@baylibre.com>
Date:   Thu, 13 Dec 2018 09:49:05 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Sunny Luo <sunny.luo@...ogic.com>, Mark Brown <broonie@...nel.org>
Cc:     Yixun Lan <yixun.lan@...ogic.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>,
        Jianxin Pan <jianxin.pan@...ogic.com>,
        Xingyu Chen <xingyu.chen@...ogic.com>,
        linux-spi@...r.kernel.org, linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] spi: meson-axg: support MAX 80M clock

Hi Sunny,

On 13/12/2018 09:39, Sunny Luo wrote:
> The SPICC controller in Meson-AXG is capable of running at 80M clock.
> The ASIC IP is improved and the clock is actually running higher than
> previous old SoCs.
> 
> Signed-off-by: Sunny Luo <sunny.luo@...ogic.com>
> Signed-off-by: Yixun Lan <yixun.lan@...ogic.com>
> ---
>  drivers/spi/spi-meson-spicc.c | 37 +++++++++++++++++++++++++++++--------
>  1 file changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
> index 7fe4488..b56249d 100644
> --- a/drivers/spi/spi-meson-spicc.c
> +++ b/drivers/spi/spi-meson-spicc.c
> @@ -9,11 +9,13 @@
>  
>  #include <linux/bitfield.h>
>  #include <linux/clk.h>
> +#include <linux/clk-provider.h>
>  #include <linux/device.h>
>  #include <linux/io.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  #include <linux/spi/spi.h>
>  #include <linux/types.h>
> @@ -34,7 +36,6 @@
>   *   to have a CS go down over the full transfer
>   */
>  
> -#define SPICC_MAX_FREQ	30000000
>  #define SPICC_MAX_BURST	128
>  
>  /* Register Map */
> @@ -120,6 +121,10 @@
>  #define SPICC_BURST_MAX	16
>  #define SPICC_FIFO_HALF 10
>  
> +struct meson_spicc_data {
> +	unsigned int			max_speed_hz;
> +};
> +
>  struct meson_spicc_device {
>  	struct spi_master		*master;
>  	struct platform_device		*pdev;
> @@ -127,6 +132,7 @@ struct meson_spicc_device {
>  	struct clk			*core;
>  	struct spi_message		*message;
>  	struct spi_transfer		*xfer;
> +	const struct meson_spicc_data	*data;
>  	u8				*tx_buf;
>  	u8				*rx_buf;
>  	unsigned int			bytes_per_word;
> @@ -517,6 +523,9 @@ static int meson_spicc_probe(struct platform_device *pdev)
>  	spicc->pdev = pdev;
>  	platform_set_drvdata(pdev, spicc);
>  
> +	spicc->data = (const struct meson_spicc_data *)
> +		of_device_get_match_data(&pdev->dev);
> +
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	spicc->base = devm_ioremap_resource(&pdev->dev, res);
>  	if (IS_ERR(spicc->base)) {
> @@ -567,11 +576,9 @@ static int meson_spicc_probe(struct platform_device *pdev)
>  	master->unprepare_transfer_hardware = meson_spicc_unprepare_transfer;
>  	master->transfer_one = meson_spicc_transfer_one;
>  
> -	/* Setup max rate according to the Meson GX datasheet */
> -	if ((rate >> 2) > SPICC_MAX_FREQ)
> -		master->max_speed_hz = SPICC_MAX_FREQ;
> -	else
> -		master->max_speed_hz = rate >> 2;
> +	/* Setup max rate according to the Meson datasheet */
> +	master->max_speed_hz = min_t(unsigned int, rate >> 1,
> +				     spicc->data->max_speed_hz);

I think "rate >> 1" here depends on patch 3, either move patch 3 before this one
or keep "rate >> 2" and change it back to "rate >> 1" on patch 3.

>  
>  	ret = devm_spi_register_master(&pdev->dev, master);
>  	if (ret) {
> @@ -602,9 +609,23 @@ static int meson_spicc_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static const struct meson_spicc_data meson_spicc_gx_data = {
> +	.max_speed_hz	= 30000000,
> +};
> +
> +static const struct meson_spicc_data meson_spicc_axg_data = {
> +	.max_speed_hz	= 80000000,
> +};
> +
>  static const struct of_device_id meson_spicc_of_match[] = {
> -	{ .compatible = "amlogic,meson-gx-spicc", },
> -	{ .compatible = "amlogic,meson-axg-spicc", },
> +	{
> +		.compatible	= "amlogic,meson-gx-spicc",
> +		.data		= &meson_spicc_gx_data,
> +	},
> +	{
> +		.compatible = "amlogic,meson-axg-spicc",
> +		.data		= &meson_spicc_axg_data,
> +	},
>  	{ /* sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, meson_spicc_of_match);
>