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Date: Mon, 10 Jan 2022 13:11:50 +0100
From: Jiri Slaby <jirislaby@...nel.org>
To: Yu Tu <yu.tu@...ogic.com>, linux-serial@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Rob Herring <robh+dt@...nel.org>,
Neil Armstrong <narmstrong@...libre.com>,
Kevin Hilman <khilman@...libre.com>,
Jerome Brunet <jbrunet@...libre.com>,
Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: Re: [PATCH V5 3/5] tty: serial: meson: Using the common clock code
describe.
Hi,
"Subject: Using the common clock code describe."
Please reformulate that ^^^ -- I cannot make any sense of it. And avoid
adding a period to the subject. PLease see others' commit logs.
On 10. 01. 22, 11:42, Yu Tu wrote:
> Using the common Clock code to describe the UART baud rate clock
> makes it easier for the UART driver to be compatible with the
> baud rate requirements of the UART IP on different meson chips.
> Signed-off-by: Yu Tu <yu.tu@...ogic.com>
> ---
> drivers/tty/serial/meson_uart.c | 224 +++++++++++++++++++++++---------
> 1 file changed, 163 insertions(+), 61 deletions(-)
>
> diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
> index 7570958d010c..1004fd0b0c9e 100644
> --- a/drivers/tty/serial/meson_uart.c
> +++ b/drivers/tty/serial/meson_uart.c
> @@ -6,6 +6,7 @@
> */
>
> #include <linux/clk.h>
> +#include <linux/clk-provider.h>
> #include <linux/console.h>
> #include <linux/delay.h>
> #include <linux/init.h>
> @@ -65,9 +66,7 @@
> #define AML_UART_RECV_IRQ(c) ((c) & 0xff)
>
> /* AML_UART_REG5 bits */
> -#define AML_UART_BAUD_MASK 0x7fffff
> #define AML_UART_BAUD_USE BIT(23)
> -#define AML_UART_BAUD_XTAL BIT(24)
>
> #define AML_UART_PORT_NUM 12
> #define AML_UART_PORT_OFFSET 6
> @@ -76,6 +75,13 @@
> #define AML_UART_POLL_USEC 5
> #define AML_UART_TIMEOUT_USEC 10000
>
> +struct meson_uart_data {
> + struct uart_port port;
> + struct clk *pclk;
> + struct clk *baud_clk;
> + bool use_xtal_clk;
> +};
> +
> static struct uart_driver meson_uart_driver;
>
> static struct uart_port *meson_ports[AML_UART_PORT_NUM];
> @@ -268,14 +274,11 @@ static void meson_uart_reset(struct uart_port *port)
> static int meson_uart_startup(struct uart_port *port)
> {
> u32 val;
> - int ret = 0;
> + int ret;
>
> - val = readl(port->membase + AML_UART_CONTROL);
> - val |= AML_UART_CLEAR_ERR;
> - writel(val, port->membase + AML_UART_CONTROL);
> - val &= ~AML_UART_CLEAR_ERR;
> - writel(val, port->membase + AML_UART_CONTROL);
> + meson_uart_reset(port);
Why is this OK? We didn't use to reset it.
And why is this not done in a separate patch?
> + val = readl(port->membase + AML_UART_CONTROL);
> val |= (AML_UART_RX_EN | AML_UART_TX_EN);
> writel(val, port->membase + AML_UART_CONTROL);
>
> @@ -293,19 +296,17 @@ static int meson_uart_startup(struct uart_port *port)
>
> static void meson_uart_change_speed(struct uart_port *port, unsigned long baud)
> {
> + struct meson_uart_data *private_data = port->private_data;
> u32 val;
>
> while (!meson_uart_tx_empty(port))
> cpu_relax();
>
> - if (port->uartclk == 24000000) {
> - val = ((port->uartclk / 3) / baud) - 1;
> - val |= AML_UART_BAUD_XTAL;
> - } else {
> - val = ((port->uartclk * 10 / (baud * 4) + 5) / 10) - 1;
> - }
> + val = readl(port->membase + AML_UART_REG5);
> val |= AML_UART_BAUD_USE;
> writel(val, port->membase + AML_UART_REG5);
> +
> + clk_set_rate(private_data->baud_clk, baud);
> }
>
> static void meson_uart_set_termios(struct uart_port *port,
> @@ -395,11 +396,27 @@ static int meson_uart_verify_port(struct uart_port *port,
>
> static void meson_uart_release_port(struct uart_port *port)
> {
> - /* nothing to do */
> + struct meson_uart_data *private_data = port->private_data;
> +
> + clk_disable_unprepare(private_data->baud_clk);
> + clk_disable_unprepare(private_data->pclk);
> }
>
> static int meson_uart_request_port(struct uart_port *port)
> {
> + struct meson_uart_data *private_data = port->private_data;
> + int ret;
> +
> + ret = clk_prepare_enable(private_data->pclk);
> + if (ret)
> + return ret;
> +
> + ret = clk_prepare_enable(private_data->baud_clk);
> + if (ret) {
> + clk_disable_unprepare(private_data->pclk);
> + return ret;
> + }
> +
> return 0;
> }
>
> @@ -629,55 +646,105 @@ static struct uart_driver meson_uart_driver = {
> .cons = MESON_SERIAL_CONSOLE,
> };
>
> -static inline struct clk *meson_uart_probe_clock(struct device *dev,
> - const char *id)
> +#define CLK_NAME(name) \
> +({\
> + char clk_name[32];\
> + snprintf(clk_name, sizeof(clk_name), "%s#%s", dev_name(port->dev), #name);\
> + clk_name;\
> +})
This is cryptic and duplicates the variable on the stack. Why not expand
the macro and delete it then?
> +
> +static struct clk_div_table xtal_div_table[] = {
> + { 0, 3 },
An extra space here and there:
> + { 1, 1 },
> + { 2, 2 },
> + { 3, 2 },
> +};
> +
> +static int meson_uart_probe_clocks(struct uart_port *port)
> {
> - struct clk *clk = NULL;
> - int ret;
> + struct meson_uart_data *private_data = port->private_data;
> + struct clk *clk_baud, *clk_xtal;
> + struct clk_hw *hw;
> + struct clk_parent_data use_xtal_mux_parents[2] = {
> + { .index = -1, },
> + { .index = -1, },
> + };
>
> - clk = devm_clk_get(dev, id);
> - if (IS_ERR(clk))
> - return clk;
> + private_data->pclk = devm_clk_get(port->dev, "pclk");
> + if (IS_ERR(private_data->pclk))
> + return dev_err_probe(port->dev, PTR_ERR(private_data->pclk),
> + "Failed to get the 'pclk' clock\n");
>
> - ret = clk_prepare_enable(clk);
> - if (ret) {
> - dev_err(dev, "couldn't enable clk\n");
> - return ERR_PTR(ret);
> + clk_baud = devm_clk_get(port->dev, "baud");
> + if (IS_ERR(clk_baud)) {
> + dev_err(port->dev, "Failed to get the 'baud' clock\n");
> + return PTR_ERR(clk_baud);
> }
>
> - devm_add_action_or_reset(dev,
> - (void(*)(void *))clk_disable_unprepare,
> - clk);
> -
> - return clk;
> -}
> -
> -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;
> -
> - clk_pclk = meson_uart_probe_clock(&pdev->dev, "pclk");
> - if (IS_ERR(clk_pclk))
> - return PTR_ERR(clk_pclk);
> -
> - clk_xtal = meson_uart_probe_clock(&pdev->dev, "xtal");
> + clk_xtal = devm_clk_get(port->dev, "xtal");
> if (IS_ERR(clk_xtal))
> - return PTR_ERR(clk_xtal);
> -
> - clk_baud = meson_uart_probe_clock(&pdev->dev, "baud");
> - if (IS_ERR(clk_baud))
> - return PTR_ERR(clk_baud);
> + return dev_err_probe(port->dev, PTR_ERR(clk_xtal),
> + "Failed to get the 'xtal' clock\n");
> +
> + if (private_data->use_xtal_clk) {
> + hw = devm_clk_hw_register_divider_table(port->dev,
> + CLK_NAME(xtal_div),
> + __clk_get_name(clk_baud),
> + CLK_SET_RATE_NO_REPARENT,
> + port->membase + AML_UART_REG5,
> + 26, 2,
> + CLK_DIVIDER_READ_ONLY,
> + xtal_div_table, NULL);
> + if (IS_ERR(hw))
> + return PTR_ERR(hw);
> +
> + use_xtal_mux_parents[1].hw = hw;
> + } else {
> + hw = devm_clk_hw_register_fixed_factor(port->dev,
> + CLK_NAME(clk81_div4),
> + __clk_get_name(clk_baud),
> + CLK_SET_RATE_NO_REPARENT,
> + 1, 4);
> + if (IS_ERR(hw))
> + return PTR_ERR(hw);
> +
> + use_xtal_mux_parents[0].hw = hw;
> + }
>
> - port->uartclk = clk_get_rate(clk_baud);
> + hw = __devm_clk_hw_register_mux(port->dev, NULL,
> + CLK_NAME(use_xtal),
> + ARRAY_SIZE(use_xtal_mux_parents),
> + NULL, NULL,
> + use_xtal_mux_parents,
> + CLK_SET_RATE_PARENT,
> + port->membase + AML_UART_REG5,
> + 24, 0x1,
> + CLK_MUX_READ_ONLY,
> + NULL, NULL);
> + if (IS_ERR(hw))
> + return PTR_ERR(hw);
> +
> + port->uartclk = clk_hw_get_rate(hw);
> +
> + hw = devm_clk_hw_register_divider(port->dev,
> + CLK_NAME(baud_div),
> + clk_hw_get_name(hw),
> + CLK_SET_RATE_PARENT,
> + port->membase + AML_UART_REG5,
> + 0, 23,
> + CLK_DIVIDER_ROUND_CLOSEST,
> + NULL);
> + if (IS_ERR(hw))
> + return PTR_ERR(hw);
> +
> + private_data->baud_clk = clk_hw_get_clk(hw, "baud_rate");
>
> return 0;
> }
--
js
suse labs
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