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Date:   Tue, 30 May 2023 11:36:00 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Jisheng Zhang <jszhang@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Jiri Slaby <jirislaby@kernel.org>,
        linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
        devicetree@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH v4 04/10] serial: bflb_uart: add Bouffalolab UART Driver
Message-ID: <2023053010-gondola-luminous-f5e7@gregkh>
References: <20230518152244.2178-1-jszhang@kernel.org>
 <20230518152244.2178-5-jszhang@kernel.org>
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In-Reply-To: <20230518152244.2178-5-jszhang@kernel.org>
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On Thu, May 18, 2023 at 11:22:38PM +0800, Jisheng Zhang wrote:
> Add the driver for Bouffalolab UART IP which is found in Bouffalolab
> SoCs such as bl808.

New uarts are being created that are NOT 8250-like?  Why????


> 
> UART driver probe will create path named "/dev/ttySx".
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  drivers/tty/serial/Kconfig       |  18 +
>  drivers/tty/serial/Makefile      |   1 +
>  drivers/tty/serial/bflb_uart.c   | 586 +++++++++++++++++++++++++++++++
>  include/uapi/linux/serial_core.h |   3 +
>  4 files changed, 608 insertions(+)
>  create mode 100644 drivers/tty/serial/bflb_uart.c
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 398e5aac2e77..abc30a0713f5 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -179,6 +179,24 @@ config SERIAL_ATMEL_TTYAT
>  
>  	  Say Y if you have an external 8250/16C550 UART.  If unsure, say N.
>  
> +config SERIAL_BFLB
> +	tristate "Bouffalolab serial port support"
> +	select SERIAL_CORE
> +	depends on COMMON_CLK
> +	help
> +	  This enables the driver for the Bouffalolab's serial.
> +
> +config SERIAL_BFLB_CONSOLE
> +	bool "Support for console on Bouffalolab serial port"
> +	depends on SERIAL_BFLB=y
> +	select SERIAL_CORE_CONSOLE
> +	select SERIAL_EARLYCON
> +	help
> +	  Say Y here if you wish to use a Bouffalolab UART as the
> +	  system console (the system console is the device which
> +	  receives all kernel messages and warnings and which allows
> +	  logins in single user mode) as /dev/ttySn.
> +
>  config SERIAL_KGDB_NMI
>  	bool "Serial console over KGDB NMI debugger port"
>  	depends on KGDB_SERIAL_CONSOLE
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index cd9afd9e3018..5788a708d327 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -25,6 +25,7 @@ obj-$(CONFIG_SERIAL_8250) += 8250/
>  
>  obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
>  obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
> +obj-$(CONFIG_SERIAL_BFLB) += bflb_uart.o
>  obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o
>  obj-$(CONFIG_SERIAL_PXA_NON8250) += pxa.o
>  obj-$(CONFIG_SERIAL_SA1100) += sa1100.o
> diff --git a/drivers/tty/serial/bflb_uart.c b/drivers/tty/serial/bflb_uart.c
> new file mode 100644
> index 000000000000..3f80bba8599a
> --- /dev/null
> +++ b/drivers/tty/serial/bflb_uart.c
> @@ -0,0 +1,586 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Based on bflb_uart.c, by Bouffalolab team
> + *
> + * Copyright (C) 2022 Jisheng Zhang <jszhang@kernel.org>

It is 2023 :)

> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/console.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/serial.h>
> +#include <linux/serial_core.h>
> +#include <linux/tty.h>
> +#include <linux/tty_flip.h>
> +
> +#define UART_UTX_CONFIG			0x00
> +#define  UART_CR_UTX_EN			BIT(0)
> +#define  UART_CR_UTX_CTS_EN		BIT(1)
> +#define  UART_CR_UTX_FRM_EN		BIT(2)
> +#define  UART_CR_UTX_PRT_EN		BIT(4)
> +#define  UART_CR_UTX_PRT_SEL		BIT(5)
> +#define  UART_CR_UTX_BIT_CNT_D_MSK	GENMASK(10, 8)
> +#define  UART_CR_UTX_BIT_CNT_P_MSK	GENMASK(12, 11)
> +#define UART_URX_CONFIG			0x04
> +#define  UART_CR_URX_EN			BIT(0)
> +#define  UART_CR_URX_PRT_EN		BIT(4)
> +#define  UART_CR_URX_PRT_SEL		BIT(5)
> +#define  UART_CR_URX_BIT_CNT_D_MSK	GENMASK(10, 8)
> +#define UART_BIT_PRD			0x08
> +#define  UART_CR_UTX_BIT_PRD_MSK	GENMASK(15, 0)
> +#define  UART_CR_URX_BIT_PRD_MSK	GENMASK(31, 16)
> +#define UART_DATA_CONFIG		0x0c
> +#define  UART_CR_UART_BIT_INV		BIT(0)
> +#define UART_URX_RTO_TIMER		0x18
> +#define  UART_CR_URX_RTO_VALUE_MSK	GENMASK(7, 0)
> +#define UART_SW_MODE			0x1c
> +#define UART_INT_STS			0x20
> +#define  UART_UTX_END_INT		BIT(0)
> +#define  UART_URX_END_INT		BIT(1)
> +#define  UART_UTX_FIFO_INT		BIT(2)
> +#define  UART_URX_FIFO_INT		BIT(3)
> +#define  UART_URX_RTO_INT		BIT(4)
> +#define  UART_URX_PCE_INT		BIT(5)
> +#define  UART_UTX_FER_INT		BIT(6)
> +#define  UART_URX_FER_INT		BIT(7)
> +#define  UART_URX_LSE_INT		BIT(8)
> +#define UART_INT_MASK			0x24
> +#define UART_INT_CLEAR			0x28
> +#define UART_INT_EN			0x2c
> +#define UART_STATUS			0x30
> +#define  UART_STS_UTX_BUS_BUSY		BIT(0)
> +#define UART_FIFO_CONFIG_0		0x80
> +#define  UART_DMA_TX_EN			BIT(0)
> +#define  UART_DMA_RX_EN			BIT(1)
> +#define  UART_TX_FIFO_CLR		BIT(2)
> +#define  UART_RX_FIFO_CLR		BIT(3)
> +#define  UART_TX_FIFO_OVERFLOW		BIT(4)
> +#define  UART_TX_FIFO_UNDERFLOW		BIT(5)
> +#define  UART_RX_FIFO_OVERFLOW		BIT(6)
> +#define  UART_RX_FIFO_UNDERFLOW		BIT(7)
> +#define UART_FIFO_CONFIG_1		0x84
> +#define  UART_TX_FIFO_CNT_MSK		GENMASK(5, 0)
> +#define  UART_RX_FIFO_CNT_MSK		GENMASK(13, 8)
> +#define  UART_TX_FIFO_TH_MSK		GENMASK(20, 16)
> +#define  UART_RX_FIFO_TH_MSK		GENMASK(28, 24)
> +#define UART_FIFO_WDATA			0x88
> +#define UART_FIFO_RDATA			0x8c
> +#define  UART_FIFO_RDATA_MSK		GENMASK(7, 0)
> +
> +#define BFLB_UART_MAXPORTS		8
> +#define BFLB_UART_BAUD			2000000
> +#define BFLB_UART_RX_FIFO_TH		7
> +#define BFLB_UART_TX_FIFO_TH		15
> +#define BFLB_UART_URX_RTO_TIME		0x4f
> +
> +struct bflb_uart_port {
> +	struct uart_port port;
> +	struct clk *clk;
> +};
> +
> +static struct bflb_uart_port *bflb_uart_ports[BFLB_UART_MAXPORTS];
> +
> +static inline u32 rdl(struct uart_port *port, u32 reg)
> +{
> +	return readl_relaxed(port->membase + reg);
> +}
> +
> +static inline void wrl(struct uart_port *port, u32 reg, u32 value)
> +{
> +	writel_relaxed(value, port->membase + reg);
> +}
> +
> +static inline void wrb(struct uart_port *port, u32 reg, u8 value)
> +{
> +	writeb_relaxed(value, port->membase + reg);
> +}
> +
> +static unsigned int bflb_uart_tx_empty(struct uart_port *port)
> +{
> +	return (rdl(port, UART_FIFO_CONFIG_1) & UART_TX_FIFO_CNT_MSK) ? TIOCSER_TEMT : 0;
> +}
> +
> +static unsigned int bflb_uart_get_mctrl(struct uart_port *port)
> +{
> +	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
> +}
> +
> +static void bflb_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
> +{
> +}

Why is a blank function required here?


> --- a/include/uapi/linux/serial_core.h
> +++ b/include/uapi/linux/serial_core.h
> @@ -279,4 +279,7 @@
>  /* Sunplus UART */
>  #define PORT_SUNPLUS	123
>  
> +/* Bouffalolab UART */
> +#define PORT_BFLB	124

Why is this required?  What userspace code is going to need this?

thanks,

greg k-h