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Message-ID: <4d07d6c0-e320-60cf-740f-c39bfed19c0d@baylibre.com>
Date: Mon, 6 Dec 2021 11:50:42 +0100
From: Neil Armstrong <narmstrong@...libre.com>
To: "xianwei.zhao" <xianwei.zhao@...ogic.com>,
linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>,
Kevin Hilman <khilman@...libre.com>,
Jerome Brunet <jbrunet@...libre.com>,
Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: Re: [PATCH] serial: meson: make the current driver compatible with S4
Hi,
On 06/12/2021 11:02, xianwei.zhao wrote:
> Because S4 UART use a different clock source, the baud rate calculation need to be updated.
> Reset the UART during initialization to clear previous status.
>
> Signed-off-by: xianwei.zhao <xianwei.zhao@...ogic.com>
> ---
> drivers/tty/serial/meson_uart.c | 50 +++++++++++++++++++++++++++------
> 1 file changed, 42 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
> index efee3935917f..15a992ee6a28 100644
> --- a/drivers/tty/serial/meson_uart.c
> +++ b/drivers/tty/serial/meson_uart.c
> @@ -65,9 +65,11 @@
> #define AML_UART_RECV_IRQ(c) ((c) & 0xff)
>
> /* AML_UART_REG5 bits */
> -#define AML_UART_BAUD_MASK 0x7fffff
> +#define AML_UART_BAUD_MASK GENMASK(22, 0)
> #define AML_UART_BAUD_USE BIT(23)
> #define AML_UART_BAUD_XTAL BIT(24)
> +#define AML_UART_BAUD_XTAL_TICK BIT(26)
> +#define AML_UART_BAUD_XTAL_DIV2 BIT(27)
>
> #define AML_UART_PORT_NUM 12
> #define AML_UART_PORT_OFFSET 6
> @@ -80,6 +82,14 @@ static struct uart_driver meson_uart_driver;
>
> static struct uart_port *meson_ports[AML_UART_PORT_NUM];
>
> +/*
> + * struct aml_uart - device data
> + * @xtal_tick_en: A clock source that calculates baud rates
> + */
> +struct aml_uart {
please change to a better name like meson_uart_data and pass it as data of meson_uart_dt_match
> + unsigned int xtal_tick_en;
> +};
> +
> static void meson_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
> {
> }
> @@ -103,7 +113,7 @@ static void meson_uart_stop_tx(struct uart_port *port)
> u32 val;
>
> val = readl(port->membase + AML_UART_CONTROL);
> - val &= ~AML_UART_TX_INT_EN;
> + val &= ~AML_UART_TX_EN;
Seems to be a cosmetic change, please split this in a separate patch.
> writel(val, port->membase + AML_UART_CONTROL);
> }
>
> @@ -121,12 +131,12 @@ static void meson_uart_shutdown(struct uart_port *port)
> unsigned long flags;
> u32 val;
>
> - free_irq(port->irq, port);
> + devm_free_irq(port->dev, port->irq, port);
Please split this in a separate patch
>
> spin_lock_irqsave(&port->lock, flags);
>
> val = readl(port->membase + AML_UART_CONTROL);
> - val &= ~AML_UART_RX_EN;
> + val &= ~(AML_UART_RX_EN | AML_UART_TX_EN);
Seems it fixes a bug, split in a separate patch.
> val &= ~(AML_UART_RX_INT_EN | AML_UART_TX_INT_EN);
> writel(val, port->membase + AML_UART_CONTROL);
>
> @@ -270,6 +280,7 @@ static int meson_uart_startup(struct uart_port *port)
> u32 val;
> int ret = 0;
>
> + meson_uart_reset(port);
Same, split in a separate patch
> val = readl(port->membase + AML_UART_CONTROL);
> val |= AML_UART_CLEAR_ERR;
> writel(val, port->membase + AML_UART_CONTROL);
> @@ -285,24 +296,37 @@ static int meson_uart_startup(struct uart_port *port)
> val = (AML_UART_RECV_IRQ(1) | AML_UART_XMIT_IRQ(port->fifosize / 2));
> writel(val, port->membase + AML_UART_MISC);
>
> - ret = request_irq(port->irq, meson_uart_interrupt, 0,
> - port->name, port);
> + ret = devm_request_irq(port->dev, port->irq, meson_uart_interrupt,
> + IRQF_SHARED, port->name, port);
Same, split in a separate patch
>
> return ret;
> }
>
> static void meson_uart_change_speed(struct uart_port *port, unsigned long baud)
> {
> + struct aml_uart *aml_uart_data = port->private_data;
> u32 val;
>
> while (!meson_uart_tx_empty(port))
> cpu_relax();
>
> + val = readl_relaxed(port->membase + AML_UART_REG5);
> + val &= ~AML_UART_BAUD_MASK;
> +
> if (port->uartclk == 24000000) {
> - val = ((port->uartclk / 3) / baud) - 1;
> - val |= AML_UART_BAUD_XTAL;
> + if (aml_uart_data->xtal_tick_en) {
> + val = (port->uartclk / 2 + baud / 2) / baud - 1;
> + val |= (AML_UART_BAUD_XTAL | AML_UART_BAUD_XTAL_DIV2);
This should be triggered by a value in match data with a new compatible.
> + } else {
> + val = ((port->uartclk / 3) + baud / 2) / baud - 1;
> + val &= (~(AML_UART_BAUD_XTAL_TICK |
> + AML_UART_BAUD_XTAL_DIV2));
> + val |= AML_UART_BAUD_XTAL;
> + }
> } else {
> val = ((port->uartclk * 10 / (baud * 4) + 5) / 10) - 1;
> + val &= (~(AML_UART_BAUD_XTAL | AML_UART_BAUD_XTAL_TICK |
> + AML_UART_BAUD_XTAL_DIV2));
> }
> val |= AML_UART_BAUD_USE;
> writel(val, port->membase + AML_UART_REG5);
> @@ -715,6 +739,7 @@ static int meson_uart_probe(struct platform_device *pdev)
> {
> struct resource *res_mem, *res_irq;
> struct uart_port *port;
> + struct aml_uart *aml_uart_data;
> u32 fifosize = 64; /* Default is 64, 128 for EE UART_0 */
> int ret = 0;
>
> @@ -754,6 +779,14 @@ static int meson_uart_probe(struct platform_device *pdev)
> if (!port)
> return -ENOMEM;
>
> + aml_uart_data = devm_kzalloc(&pdev->dev, sizeof(struct aml_uart),
> + GFP_KERNEL);
> + if (!aml_uart_data)
> + return -ENOMEM;
> +
> + of_property_read_u32(pdev->dev.of_node, "xtal_tick_en",
> + &aml_uart_data->xtal_tick_en);
This property is not documented in the bindings, instead introduce
a new compatible for the S4 and pass the "aml_uart" as the meson_uart_dt_match
data pointer.
And don't forget to submit the bindings change in another separate patch.
> +
> /* 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);
> @@ -775,6 +808,7 @@ static int meson_uart_probe(struct platform_device *pdev)
> port->x_char = 0;
> port->ops = &meson_uart_ops;
> port->fifosize = fifosize;
> + port->private_data = aml_uart_data;
>
> meson_ports[pdev->id] = port;
> platform_set_drvdata(pdev, port);
>
> base-commit: 3f19fed8d0daed6e0e04b130d203d4333b757901
>
Thanks,
Neil
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