Message-ID: <1497260344.3086.8.camel@baylibre.com>
Subject: Re: [PATCH v4 2/7] tty/serial: meson_uart: update to stable bindings
From: Jerome Brunet <jbrunet@baylibre.com>
To: Neil Armstrong <narmstrong@baylibre.com>, gregkh@linuxfoundation.org,
        khilman@baylibre.com
Cc: linux-kernel@vger.kernel.org, Helmut Klein <hgkr.klein@gmail.com>,
        linux-serial@vger.kernel.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org
Date: Mon, 12 Jun 2017 11:39:04 +0200
In-Reply-To: <1497001756-942-3-git-send-email-narmstrong@baylibre.com>
References: <1497001756-942-1-git-send-email-narmstrong@baylibre.com>
         <1497001756-942-3-git-send-email-narmstrong@baylibre.com>
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On Fri, 2017-06-09 at 11:49 +0200, Neil Armstrong wrote:
> From: Helmut Klein <hgkr.klein@gmail.com>
> 
> This patch handle the stable UART bindings but also keeps compatibility
> with the legacy non-stable bindings until all boards uses them.
> 
> Signed-off-by: Helmut Klein <hgkr.klein@gmail.com>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
>  drivers/tty/serial/meson_uart.c | 109 +++++++++++++++++++++++++++++++++++++
> ---
>  1 file changed, 103 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
> index 60f1679..d2c8136 100644
> --- a/drivers/tty/serial/meson_uart.c
> +++ b/drivers/tty/serial/meson_uart.c
> @@ -579,8 +579,12 @@ static void meson_serial_early_console_write(struct
> console *co,
>  	device->con->write = meson_serial_early_console_write;
>  	return 0;
>  }
> +/* Legacy bindings, should be removed when no more used */
>  OF_EARLYCON_DECLARE(meson, "amlogic,meson-uart",
>  		    meson_serial_early_console_setup);
> +/* Stable bindings */
> +OF_EARLYCON_DECLARE(meson, "amlogic,meson-ao-uart",
> +		    meson_serial_early_console_setup);
>  
>  #define MESON_SERIAL_CONSOLE	(&meson_serial_console)
>  #else
> @@ -595,11 +599,95 @@ static void meson_serial_early_console_write(struct
> console *co,
>  	.cons		= MESON_SERIAL_CONSOLE,
>  };
>  
> +/*
> + * This function gets clocks in the legacy non-stable DT bindings.
> + * This code will be remove once all the platforms switch to the
> + * new DT bindings.
> + */
> +static int meson_uart_probe_clocks_legacy(struct platform_device *pdev,
> +					  struct uart_port *port)
> +{
> +	struct clk *clk = NULL;
> +	int ret;
> +
> +	clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
> +
> +	ret = clk_prepare_enable(clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "couldn't enable clk\n");
> +		return ret;
> +	}
> +
> +	devm_add_action_or_reset(&pdev->dev,
> +			(void(*)(void *))clk_disable_unprepare,
> +			clk);
> +
> +	port->uartclk = clk_get_rate(clk);
> +
> +	return 0;
> +}
> +
> +static int meson_uart_probe_clocks(struct platform_device *pdev,
> +				   struct uart_port *port)
> +{
> +	struct clk *clk_xtal = NULL;
> +	struct clk *clk_pclk = NULL;
> +	struct clk *clk_baud = NULL;
> +	int ret;
> +
> +	clk_pclk = devm_clk_get(&pdev->dev, "pclk");
> +	if (IS_ERR(clk_pclk))
> +		return PTR_ERR(clk_pclk);
> +
> +	clk_xtal = devm_clk_get(&pdev->dev, "xtal");
> +	if (IS_ERR(clk_xtal))
> +		return PTR_ERR(clk_xtal);
> +
> +	clk_baud = devm_clk_get(&pdev->dev, "baud");
> +	if (IS_ERR(clk_xtal))
> +		return PTR_ERR(clk_baud);
> +
> +	ret = clk_prepare_enable(clk_pclk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "couldn't enable pclk\n");
> +		return ret;
> +	}
> +
> +	devm_add_action_or_reset(&pdev->dev,
> +			(void(*)(void *))clk_disable_unprepare,
> +			clk_pclk);
> +
> +	ret = clk_prepare_enable(clk_xtal);
> +	if (ret) {
> +		dev_err(&pdev->dev, "couldn't enable xtal\n");
> +		return ret;
> +	}
> +
> +	devm_add_action_or_reset(&pdev->dev,
> +			(void(*)(void *))clk_disable_unprepare,
> +			clk_xtal);
> +
> +	ret = clk_prepare_enable(clk_baud);
> +	if (ret) {
> +		dev_err(&pdev->dev, "couldn't enable baud clk\n");
> +		return ret;
> +	}
> +
> +	devm_add_action_or_reset(&pdev->dev,
> +			(void(*)(void *))clk_disable_unprepare,
> +			clk_baud);

It's not critical but there is a lot of duplication here. Should we add an
helper function doing "get, prepare_enable, add_reset_action" with the clock
name as argument ?

Apart from this:

Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>

> +
> +	port->uartclk = clk_get_rate(clk_baud);

This was already like this, but I wonder if we should store the *clk instead of
caching the rate. Then call get_rate when appropriate

Could be done in separate patch.


> +
> +	return 0;
> +}
> +
>  static int meson_uart_probe(struct platform_device *pdev)
>  {
>  	struct resource *res_mem, *res_irq;
>  	struct uart_port *port;
> -	struct clk *clk;
>  	int ret = 0;
>  
>  	if (pdev->dev.of_node)
> @@ -625,11 +713,15 @@ static int meson_uart_probe(struct platform_device
> *pdev)
>  	if (!port)
>  		return -ENOMEM;
>  
> -	clk = clk_get(&pdev->dev, NULL);
> -	if (IS_ERR(clk))
> -		return PTR_ERR(clk);
> +	/* Use legacy way until all platforms switch to new bindings */
> +	if (of_device_is_compatible(pdev->dev.of_node, "amlogic,meson-uart"))
> +		ret = meson_uart_probe_clocks_legacy(pdev, port);
> +	else
> +		ret = meson_uart_probe_clocks(pdev, port);
> +
> +	if (ret)
> +		return ret;
>  
> -	port->uartclk = clk_get_rate(clk);
>  	port->iotype = UPIO_MEM;
>  	port->mapbase = res_mem->start;
>  	port->irq = res_irq->start;
> @@ -668,9 +760,14 @@ static int meson_uart_remove(struct platform_device
> *pdev)
>  	return 0;
>  }
>  
> -
>  static const struct of_device_id meson_uart_dt_match[] = {
> +	/* Legacy bindings, should be removed when no more used */
>  	{ .compatible = "amlogic,meson-uart" },
> +	/* Stable bindings */
> +	{ .compatible = "amlogic,meson6-uart" },
> +	{ .compatible = "amlogic,meson8-uart" },
> +	{ .compatible = "amlogic,meson8b-uart" },
> +	{ .compatible = "amlogic,meson-gx-uart" },
>  	{ /* sentinel */ },
>  };
>  MODULE_DEVICE_TABLE(of, meson_uart_dt_match);