Re: [PATCH v4 2/7] tty/serial: meson_uart: update to stable bindings

[Jerome Brunet]

On Fri, 2017-06-09 at 11:49 +0200, Neil Armstrong wrote:
> From: Helmut Klein <hgkr.klein@xxxxxxxxx>
> 
> 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@xxxxxxxxx>
> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> ---
> Âdrivers/tty/serial/meson_uart.c | 109 +++++++++++++++++++++++++++++++++++++
> ---
> Â1 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,
> Â	device->con->write = meson_serial_early_console_write;
> Â	return 0;
> Â}
> +/* Legacy bindings, should be removed when no more used */
> ÂOF_EARLYCON_DECLARE(meson, "amlogic,meson-uart",
> Â		ÂÂÂÂmeson_serial_early_console_setup);
> +/* Stable bindings */
> +OF_EARLYCON_DECLARE(meson, "amlogic,meson-ao-uart",
> +		ÂÂÂÂmeson_serial_early_console_setup);
> Â
> Â#define MESON_SERIAL_CONSOLE	(&meson_serial_console)
> Â#else
> @@ -595,11 +599,95 @@ static void meson_serial_early_console_write(struct
> console *co,
> Â	.cons		= MESON_SERIAL_CONSOLE,
> Â};
> Â
> +/*
> + * 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,
> +					ÂÂstruct 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,
> +				ÂÂÂstruct 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@xxxxxxxxxxxx>

> +
> +	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;
> +}
> +
> Âstatic int meson_uart_probe(struct platform_device *pdev)
> Â{
> Â	struct resource *res_mem, *res_irq;
> Â	struct uart_port *port;
> -	struct clk *clk;
> Â	int ret = 0;
> Â
> Â	if (pdev->dev.of_node)
> @@ -625,11 +713,15 @@ static int meson_uart_probe(struct platform_device
> *pdev)
> Â	if (!port)
> Â		return -ENOMEM;
> Â
> -	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;
> Â
> -	port->uartclk = clk_get_rate(clk);
> Â	port->iotype = UPIO_MEM;
> Â	port->mapbase = res_mem->start;
> Â	port->irq = res_irq->start;
> @@ -668,9 +760,14 @@ static int meson_uart_remove(struct platform_device
> *pdev)
> Â	return 0;
> Â}
> Â
> -
> Âstatic const struct of_device_id meson_uart_dt_match[] = {
> +	/* Legacy bindings, should be removed when no more used */
> Â	{ .compatible = "amlogic,meson-uart" },
> +	/* Stable bindings */
> +	{ .compatible = "amlogic,meson6-uart" },
> +	{ .compatible = "amlogic,meson8-uart" },
> +	{ .compatible = "amlogic,meson8b-uart" },
> +	{ .compatible = "amlogic,meson-gx-uart" },
> Â	{ /* sentinel */ },
> Â};
> ÂMODULE_DEVICE_TABLE(of, meson_uart_dt_match);