Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 22 Dec 2021 17:28:04 +0800 | Subject | Re: [PATCH 3/3] tty: serial: meson: add UART driver compatible with S4 SoC on-chip | From | Yu Tu <> |
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On 2021/12/21 15:34, Greg Kroah-Hartman wrote: > [ EXTERNAL EMAIL ] > > On Tue, Dec 21, 2021 at 03:16:34PM +0800, Yu Tu wrote: >> The S4 SoC on-chip UART uses a 12M clock as the clock source for >> calculating the baud rate of the UART. But previously, chips used 24M or >> other clock sources. So add this change. The specific clock source is >> determined by chip design. >> >> Signed-off-by: Yu Tu <yu.tu@amlogic.com> >> --- >> drivers/tty/serial/meson_uart.c | 62 +++++++++++++++++++++++++++++---- >> 1 file changed, 55 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c >> index 69450a461c48..557c24d954a2 100644 >> --- a/drivers/tty/serial/meson_uart.c >> +++ b/drivers/tty/serial/meson_uart.c >> @@ -19,6 +19,7 @@ >> #include <linux/serial_core.h> >> #include <linux/tty.h> >> #include <linux/tty_flip.h> >> +#include <linux/of_device.h> >> >> /* Register offsets */ >> #define AML_UART_WFIFO 0x00 >> @@ -68,6 +69,8 @@ >> #define AML_UART_BAUD_MASK 0x7fffff >> #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 +83,11 @@ static struct uart_driver meson_uart_driver; >> >> static struct uart_port *meson_ports[AML_UART_PORT_NUM]; >> >> +struct meson_uart_data { >> + /*A clock source that calculates baud rates*/ > > Please use spaces in your comments.
I will correct this mistake in the next patch.
> >> + unsigned int xtal_tick_en; > > What is "_en" for? > > "enabled"? > > Spell it out please. You're right.I will correct as you suggested. > > And why an unsigned int for a boolean flag? It is my thoughtless, I will correct. > >> +}; >> + >> static void meson_uart_set_mctrl(struct uart_port *port, unsigned int mctrl) >> { >> } >> @@ -294,16 +302,29 @@ 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 *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 (uart_data->xtal_tick_en) { >> + val = (port->uartclk / 2 + baud / 2) / baud - 1; >> + val |= (AML_UART_BAUD_XTAL | AML_UART_BAUD_XTAL_DIV2); >> + } 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); >> @@ -714,6 +735,7 @@ static int meson_uart_probe(struct platform_device *pdev) >> { >> struct resource *res_mem, *res_irq; >> struct uart_port *port; >> + struct meson_uart_data *uart_data; >> int ret = 0; >> int id = -1; >> >> @@ -729,6 +751,10 @@ static int meson_uart_probe(struct platform_device *pdev) >> } >> } >> >> + uart_data = of_device_get_match_data(&pdev->dev); >> + if (!uart_data) >> + return -EINVAL; > > Wrong spacing. > > Always use checkpatch.pl on your patches before sending them out. Sorry, this is a rookie mistake.But I did check it locally before sending it. I will follow your advice strictly later. > > And did you just break existing systems? Do you know if all older ones > will still work with that call? > It does affect older systems, but the new and older baud rates are not the same. I checked the documents before I made any changes. So this change is compatible with the older. >> + >> if (pdev->id < 0 || pdev->id >= AML_UART_PORT_NUM) >> return -EINVAL; >> >> @@ -770,6 +796,7 @@ static int meson_uart_probe(struct platform_device *pdev) >> port->x_char = 0; >> port->ops = &meson_uart_ops; >> port->fifosize = 64; >> + port->private_data = uart_data; >> >> meson_ports[pdev->id] = port; >> platform_set_drvdata(pdev, port); >> @@ -798,14 +825,35 @@ static int meson_uart_remove(struct platform_device *pdev) >> return 0; >> } >> >> +static const struct meson_uart_data meson_uart_data = { >> + .xtal_tick_en = 0, >> +}; >> + >> +static const struct meson_uart_data s4_meson_uart_data = { >> + .xtal_tick_en = 1, >> +}; > > As your whole structure just has one bit, why not just use that as the > data value, instead of a structure? No need to be complex here at all. > It is my thoughtless, I will correct. > thanks, > > greg k-h >
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