linux-kernel - Re: [PATCH v2 01/11] serial:st-asc: Add ST ASC driver.

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Date:	Mon, 10 Jun 2013 12:53:55 +0100
From:	Srinivas KANDAGATLA <srinivas.kandagatla@...com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	"David S. Miller" <davem@...emloft.net>,
	devicetree-discuss@...ts.ozlabs.org,
	Grant Likely <grant.likely@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	John Stultz <john.stultz@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org, Mark Brown <broonie@...nel.org>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Olof Johansson <olof@...om.net>,
	Rob Herring <rob.herring@...xeda.com>,
	Rob Landley <rob@...dley.net>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Stephen Gallimore <stephen.gallimore@...com>,
	Stuart Menefy <stuart.menefy@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tony Prisk <linux@...sktech.co.nz>
Subject: Re: [PATCH v2 01/11] serial:st-asc: Add ST ASC driver.

Thankyou for your comment and suggestion,
I will fix the POSIX compliant issue.

On 10/06/13 10:35, Russell King - ARM Linux wrote:
> On Mon, Jun 10, 2013 at 10:21:00AM +0100, Srinivas KANDAGATLA wrote:
>> This patch adds support to ASC (asynchronous serial controller)
>> driver, which is basically a standard serial driver. This IP is common
>> across all the ST parts for settop box platforms.
>>
>> ASC is embedded in ST COMMS IP block. It supports Rx & Tx functionality.
>> It support all industry standard baud rates.
> 
> Your driver is not POSIX compliant.
> 
>> +		for (; count != 0; count--) {
>> +			c = asc_in(port, ASC_RXBUF);
>> +			flag = TTY_NORMAL;
>> +			port->icount.rx++;
>> +
>> +			if (unlikely(c & ASC_RXBUF_FE)) {
>> +				if (c == ASC_RXBUF_FE) {
>> +					port->icount.brk++;
>> +					if (uart_handle_break(port))
>> +						continue;
>> +					flag = TTY_BREAK;
>> +				} else {
>> +					port->icount.frame++;
>> +					flag = TTY_FRAME;
>> +				}
>> +			} else if (ascport->check_parity &&
>> +				   unlikely(c & ASC_RXBUF_PE)) {
>> +				port->icount.parity++;
>> +				flag = TTY_PARITY;
>> +			}
>> +
>> +			if (uart_handle_sysrq_char(port, c))
>> +				continue;
>> +			tty_insert_flip_char(tport, c & 0xff, flag);
>> +		}
>> +		if (overrun) {
>> +			port->icount.overrun++;
>> +			tty_insert_flip_char(tport, 0, TTY_OVERRUN);
>> +		}
> 
> No support for ignoring error conditions.  No support for ignoring all
> input... and:
> 
>> +static void asc_set_termios(struct uart_port *port, struct ktermios *termios,
>> +			    struct ktermios *old)
>> +{
>> +	struct asc_port *ascport = to_asc_port(port);
>> +	unsigned int baud;
>> +	u32 ctrl_val;
>> +	tcflag_t cflag;
>> +	unsigned long flags;
>> +
>> +	port->uartclk = clk_get_rate(ascport->clk);
>> +
>> +	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
>> +	cflag = termios->c_cflag;
>> +
>> +	spin_lock_irqsave(&port->lock, flags);
>> +
>> +	/* read control register */
>> +	ctrl_val = asc_in(port, ASC_CTL);
>> +
>> +	/* stop serial port and reset value */
>> +	asc_out(port, ASC_CTL, (ctrl_val & ~ASC_CTL_RUN));
>> +	ctrl_val = ASC_CTL_RXENABLE | ASC_CTL_FIFOENABLE;
>> +
>> +	/* reset fifo rx & tx */
>> +	asc_out(port, ASC_TXRESET, 1);
>> +	asc_out(port, ASC_RXRESET, 1);
>> +
>> +	/* set character length */
>> +	if ((cflag & CSIZE) == CS7) {
>> +		ctrl_val |= ASC_CTL_MODE_7BIT_PAR;
>> +	} else {
>> +		ctrl_val |= (cflag & PARENB) ?  ASC_CTL_MODE_8BIT_PAR :
>> +						ASC_CTL_MODE_8BIT;
>> +	}
>> +
>> +	ascport->check_parity = (cflag & PARENB) ? 1 : 0;
>> +
>> +	/* set stop bit */
>> +	ctrl_val |= (cflag & CSTOPB) ? ASC_CTL_STOP_2BIT : ASC_CTL_STOP_1BIT;
>> +
>> +	/* odd parity */
>> +	if (cflag & PARODD)
>> +		ctrl_val |= ASC_CTL_PARITYODD;
>> +
>> +	/* hardware flow control */
>> +	if ((cflag & CRTSCTS) && ascport->hw_flow_control)
>> +		ctrl_val |= ASC_CTL_CTSENABLE;
> 
> This doesn't reflect those facts back into the termios structure to
> indicate that they aren't supported.
> 
> Consider using uart_port's ignore and read status masks to implement
> the break, framing, parity and overrun checking in your interrupt
> handler using the same methodology as drivers like 8250, amba-pl011
> etc.  That will help you get these code sequences correct.
> 
> 

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