linux-kernel - Re: [2/3] serial: 8250: Add new port type for TI DA8xx/OMAPL13x/AM17xx/AM18xx

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Date:   Thu, 22 Dec 2016 09:21:34 -0600
From:   Franklin S Cooper Jr <fcooper@...com>
To:     David Lechner <david@...hnology.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
CC:     <devicetree@...r.kernel.org>, Axel Haslam <ahaslam@...libre.com>,
        Kevin Hilman <khilman@...nel.org>,
        Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Alexandre Bailon <abailon@...libre.com>,
        <linux-serial@...r.kernel.org>, Jiri Slaby <jslaby@...e.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [2/3] serial: 8250: Add new port type for TI
 DA8xx/OMAPL13x/AM17xx/AM18xx



On 12/20/2016 02:23 PM, David Lechner wrote:
> This adds a new UART port type for TI DA8xx/OMAPL13x/AM17xx/AM18xx. These
> SoCs have standard 8250 registers plus some extra non-standard registers.
> 
> The UART will not function unless the non-standard Power and Emulation
> Management Register (PWREMU_MGMT) is configured correctly. This is
> currently handled in arch/arm/mach-davinci/serial.c for non-device-tree
> boards. Making this part of the UART driver will allow UART to work on
> device-tree boards as well and the mach code can eventually be removed.
> 
> Signed-off-by: David Lechner <david@...hnology.com>
> ---
>  drivers/tty/serial/8250/8250_of.c   |  1 +
>  drivers/tty/serial/8250/8250_port.c | 22 ++++++++++++++++++++++
>  include/uapi/linux/serial_core.h    |  3 ++-
>  include/uapi/linux/serial_reg.h     |  8 ++++++++
>  4 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
> index d25ab1c..5281252 100644
> --- a/drivers/tty/serial/8250/8250_of.c
> +++ b/drivers/tty/serial/8250/8250_of.c
> @@ -332,6 +332,7 @@ static const struct of_device_id of_platform_serial_table[] = {
>  		.data = (void *)PORT_ALTR_16550_F128, },
>  	{ .compatible = "mrvl,mmp-uart",
>  		.data = (void *)PORT_XSCALE, },
> +	{ .compatible = "ti,da830-uart", .data = (void *)PORT_DA830, },
>  	{ /* end of list */ },
>  };
>  MODULE_DEVICE_TABLE(of, of_platform_serial_table);
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index fe4399b..ea854054 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -273,6 +273,15 @@ static const struct serial8250_config uart_config[] = {
>  		.rxtrig_bytes	= {1, 4, 8, 14},
>  		.flags		= UART_CAP_FIFO,
>  	},
> +	[PORT_DA830] = {
> +		.name		= "TI DA8xx/OMAPL13x/AM17xx/AM18xx",
> +		.fifo_size	= 16,
> +		.tx_loadsz	= 16,
> +		.fcr		= UART_FCR_DMA_SELECT | UART_FCR_ENABLE_FIFO |
> +				  UART_FCR_R_TRIG_10,
> +		.rxtrig_bytes	= {1, 4, 8, 14},
> +		.flags		= UART_CAP_FIFO | UART_CAP_AFE,
> +	},
>  };


Any reason why the fcr and flags fields are changed when compared
against PORT_16550A?
>  
>  /* Uart divisor latch read */
> @@ -2118,6 +2127,19 @@ int serial8250_do_startup(struct uart_port *port)
>  		serial_port_out(port, UART_LCR, 0);
>  	}
>  
> +	if (port->type == PORT_DA830) {
> +		/* Reset the port */
> +		serial_port_out(port, UART_IER, 0);
> +		serial_port_out(port, UART_DA830_PWREMU_MGMT, 0);
> +		mdelay(10);
> +
> +		/* Enable Tx, Rx and free run mode */
> +		serial_port_out(port, UART_DA830_PWREMU_MGMT,
> +				UART_DA830_PWREMU_MGMT_UTRST |
> +				UART_DA830_PWREMU_MGMT_URRST |
> +				UART_DA830_PWREMU_MGMT_FREE);
> +	}
> +
>  #ifdef CONFIG_SERIAL_8250_RSA
>  	/*
>  	 * If this is an RSA port, see if we can kick it up to the
> diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
> index 99dbed8..a126d05 100644
> --- a/include/uapi/linux/serial_core.h
> +++ b/include/uapi/linux/serial_core.h
> @@ -56,7 +56,8 @@
>  #define PORT_ALTR_16550_F128 28 /* Altera 16550 UART with 128 FIFOs */
>  #define PORT_RT2880	29	/* Ralink RT2880 internal UART */
>  #define PORT_16550A_FSL64 30	/* Freescale 16550 UART with 64 FIFOs */
> -#define PORT_MAX_8250	30	/* max port ID */
> +#define PORT_DA830	31	/* TI DA8xx/OMAP13x/AM17xx/AM18xx */
> +#define PORT_MAX_8250	31	/* max port ID */
>  
>  /*
>   * ARM specific type numbers.  These are not currently guaranteed
> diff --git a/include/uapi/linux/serial_reg.h b/include/uapi/linux/serial_reg.h
> index b4c0484..0e72eeb 100644
> --- a/include/uapi/linux/serial_reg.h
> +++ b/include/uapi/linux/serial_reg.h
> @@ -327,6 +327,14 @@
>  #define SERIAL_RSA_BAUD_BASE (921600)
>  #define SERIAL_RSA_BAUD_BASE_LO (SERIAL_RSA_BAUD_BASE / 8)
>  
> +/* Extra registers for TI DA8xx/OMAP13x/AM17xx/AM18xx */
> +#define UART_DA830_PWREMU_MGMT	12
> +
> +/* PWREMU_MGMT register bits */
> +#define UART_DA830_PWREMU_MGMT_FREE	(1 << 0)  /* Free-running mode */
> +#define UART_DA830_PWREMU_MGMT_URRST	(1 << 13) /* Receiver reset/enable */
> +#define UART_DA830_PWREMU_MGMT_UTRST	(1 << 14) /* Transmitter reset/enable */
> +
>  /*
>   * Extra serial register definitions for the internal UARTs
>   * in TI OMAP processors.
>