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Subject: Re: [PATCH v3 2/2] tty/serial: atmel: add ISO7816 support
To:     Ludovic Desroches <ludovic.desroches@microchip.com>,
        linux-serial@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Cc:     gregkh@linuxfoundation.org, jslaby@suse.com, arnd@arndb.de,
        richard.genoud@gmail.com, nicolas.ferre@microchip.com,
        alexandre.belloni@bootlin.com, linux-kernel@vger.kernel.org
References: <20180807130049.5957-1-ludovic.desroches@microchip.com>
 <20180807130049.5957-3-ludovic.desroches@microchip.com>
From:   Richard Genoud <richard.genoud@gmail.com>
Message-ID: <d66c4318-1d31-5c4e-3952-6b69a010b028@sorico.fr>
Date:   Thu, 9 Aug 2018 10:47:17 +0200
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Hi !

On 07/08/2018 15:00, Ludovic Desroches wrote:
> From: Nicolas Ferre <nicolas.ferre@microchip.com>
> 
> When mode is set in atmel_config_iso7816() we backup last RS232 mode
> for coming back to this mode if requested.
> Also allow setup of T=0 and T=1 parameter and basic support in set_termios
> function as well.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
> [ludovic.desroches@microchip.com: rebase, add check on fidi ratio, checkpatch fixes]
> Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
> ---
>  drivers/tty/serial/atmel_serial.c | 211 +++++++++++++++++++++++++++++++++++---
>  drivers/tty/serial/atmel_serial.h |   6 +-
>  2 files changed, 201 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index 8e4428725848..4a7ec44b0ace 100644
> --- a/drivers/tty/serial/atmel_serial.c
> +++ b/drivers/tty/serial/atmel_serial.c
> @@ -34,6 +34,7 @@
>  #include <linux/suspend.h>
>  #include <linux/mm.h>
>  
> +#include <asm/div64.h>
>  #include <asm/io.h>
>  #include <asm/ioctls.h>
>  
> @@ -83,6 +84,11 @@ static void atmel_stop_rx(struct uart_port *port);
>  
>  #define ATMEL_ISR_PASS_LIMIT	256
>  
> +struct atmel_uart_pdata {
> +	unsigned int	fidi_min;
> +	unsigned int	fidi_max;
> +};
> +
>  struct atmel_dma_buffer {
>  	unsigned char	*buf;
>  	dma_addr_t	dma_addr;
> @@ -114,6 +120,7 @@ struct atmel_uart_char {
>   */
>  struct atmel_uart_port {
>  	struct uart_port	uart;		/* uart */
> +	const struct atmel_uart_pdata *pdata;	/* SoC specific parameters */
>  	struct clk		*clk;		/* uart clock */
>  	int			may_wakeup;	/* cached value of device_may_wakeup for times we need to disable it */
>  	u32			backup_imr;	/* IMR saved during suspend */
> @@ -147,6 +154,8 @@ struct atmel_uart_port {
>  	struct circ_buf		rx_ring;
>  
>  	struct mctrl_gpios	*gpios;
> +	u32			backup_mode;	/* MR saved during iso7816 operations */
> +	u32			backup_brgr;	/* BRGR saved during iso7816 operations */
>  	unsigned int		tx_done_mask;
>  	u32			fifo_size;
>  	u32			rts_high;
> @@ -192,10 +201,34 @@ static struct console atmel_console;
>  #endif
>  
>  #if defined(CONFIG_OF)
> +static struct atmel_uart_pdata at91rm9200_pdata = {
> +	.fidi_min = 1,
> +	.fidi_max = 2047,
> +};
> +
> +static struct atmel_uart_pdata at91sam9260_pdata = {
> +	.fidi_min = 1,
> +	.fidi_max = 2047,
> +};
> +
> +static struct atmel_uart_pdata sama5d3_pdata = {
> +	.fidi_min = 3,
> +	.fidi_max = 65535,
Are you sure this is for sama5d3 ?
From the datasheets I have, 65535 is for sama5d4/sama5d2
And also, you'll have to s/atmel,at91sam9260-usart/atmel,sama5d2-usart/g
in sama5d{2,4}.dtsi

But I wonder if it could be detected via ATMEL_US_VERSION instead ?


> +};
> +
>  static const struct of_device_id atmel_serial_dt_ids[] = {
> -	{ .compatible = "atmel,at91rm9200-usart" },
> -	{ .compatible = "atmel,at91sam9260-usart" },
> -	{ /* sentinel */ }
> +	{
> +		.compatible = "atmel,at91rm9200-usart",
> +		.data = &at91rm9200_pdata,
> +	}, {
> +		.compatible = "atmel,at91sam9260-usart",
> +		.data = &at91sam9260_pdata,
> +	}, {
> +		.compatible = "atmel,sama5d3-usart",
> +		.data = &sama5d3_pdata,
> +	}, {
> +		/* sentinel */
> +	}
>  };
>  #endif
>  
> @@ -362,6 +395,127 @@ static int atmel_config_rs485(struct uart_port *port,
>  	return 0;
>  }
>  
> +static unsigned int atmel_calc_cd(struct uart_port *port,
> +				  struct serial_iso7816 *iso7816conf)
> +{
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +	unsigned int cd;
> +	u64 mck_rate;
> +
> +	mck_rate = (u64)clk_get_rate(atmel_port->clk);
> +	do_div(mck_rate, iso7816conf->clk);
> +	cd = mck_rate;
> +	return cd;
> +}
> +
> +static unsigned int atmel_calc_fidi(struct uart_port *port,
> +				    struct serial_iso7816 *iso7816conf)
> +{
> +	u64 fidi = 0;
> +
> +	if (iso7816conf->sc_fi && iso7816conf->sc_di) {
> +		fidi = (u64)iso7816conf->sc_fi;
> +		do_div(fidi, iso7816conf->sc_di);
> +	}
> +	return (u32)fidi;
> +}
> +
> +/* Enable or disable the iso7816 support */
> +/* Called with interrupts disabled */
> +static int atmel_config_iso7816(struct uart_port *port,
> +				struct serial_iso7816 *iso7816conf)
> +{
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +	unsigned int mode;
> +	unsigned int cd, fidi;
> +	int ret = 0;
> +
> +	/* Disable interrupts */
> +	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
> +
> +	mode = atmel_uart_readl(port, ATMEL_US_MR);
> +
> +	if (iso7816conf->flags & SER_ISO7816_ENABLED) {
> +		mode &= ~ATMEL_US_USMODE;
> +
> +		if (iso7816conf->tg > 255) {
> +			dev_err(port->dev, "ISO7816: Timeguard exceeding 255\n");
> +			memset(iso7816conf, 0, sizeof(struct serial_iso7816));
> +			ret = -EINVAL;
> +			goto err_out;
> +		}
> +
> +		if ((iso7816conf->flags & SER_ISO7816_T_PARAM)
> +		    == SER_ISO7816_T(0)) {
> +			mode |= ATMEL_US_USMODE_ISO7816_T0 | ATMEL_US_DSNACK;
> +		} else if ((iso7816conf->flags & SER_ISO7816_T_PARAM)
> +			   == SER_ISO7816_T(1)) {
> +			mode |= ATMEL_US_USMODE_ISO7816_T1 | ATMEL_US_INACK;
> +		} else {
> +			dev_err(port->dev, "ISO7816: Type not supported\n");
> +			memset(iso7816conf, 0, sizeof(struct serial_iso7816));
> +			ret = -EINVAL;
> +			goto err_out;
> +		}
> +
> +		mode &= ~(ATMEL_US_USCLKS | ATMEL_US_NBSTOP | ATMEL_US_PAR);
> +
> +		/* select mck clock, and output  */
> +		mode |= ATMEL_US_USCLKS_MCK | ATMEL_US_CLKO;
> +		/* set parity for normal/inverse mode + max iterations */
> +		mode |= ATMEL_US_PAR_EVEN | ATMEL_US_NBSTOP_1 | ATMEL_US_MAX_ITER(3);
> +
> +		cd = atmel_calc_cd(port, iso7816conf);
> +		fidi = atmel_calc_fidi(port, iso7816conf);
> +		if (fidi == 0) {
> +			dev_warn(port->dev, "ISO7816 fidi = 0, Generator generates no signal\n");
> +		} else if (fidi < atmel_port->pdata->fidi_min
> +			   || fidi > atmel_port->pdata->fidi_max) {
> +			dev_err(port->dev, "ISO7816 fidi = %u, value not supported\n", fidi);
> +			memset(iso7816conf, 0, sizeof(struct serial_iso7816));
> +			ret = -EINVAL;
> +			goto err_out;
> +		}
> +
> +		if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) {
> +			/* port not yet in iso7816 mode: store configuration */
> +			atmel_port->backup_mode = atmel_uart_readl(port, ATMEL_US_MR);
> +			atmel_port->backup_brgr = atmel_uart_readl(port, ATMEL_US_BRGR);
> +		}
> +
> +		atmel_uart_writel(port, ATMEL_US_TTGR, iso7816conf->tg);
> +		atmel_uart_writel(port, ATMEL_US_BRGR, cd);
> +		atmel_uart_writel(port, ATMEL_US_FIDIR, fidi);
> +
> +		atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS | ATMEL_US_RXEN);
> +		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY | ATMEL_US_NACK | ATMEL_US_ITERATION;
> +	} else {
> +		dev_dbg(port->dev, "Setting UART back to RS232\n");
> +		/* back to last RS232 settings */
> +		mode = atmel_port->backup_mode;
> +		memset(iso7816conf, 0, sizeof(struct serial_iso7816));
> +		atmel_uart_writel(port, ATMEL_US_TTGR, 0);
> +		atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->backup_brgr);
> +		atmel_uart_writel(port, ATMEL_US_FIDIR, 0x174);
> +
> +		if (atmel_use_pdc_tx(port))
> +			atmel_port->tx_done_mask = ATMEL_US_ENDTX |
> +						   ATMEL_US_TXBUFE;
> +		else
> +			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
> +	}
> +
> +	port->iso7816 = *iso7816conf;
> +
> +	atmel_uart_writel(port, ATMEL_US_MR, mode);
> +
> +err_out:
> +	/* Enable interrupts */
> +	atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);
> +
> +	return ret;
> +}
> +
>  /*
>   * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
>   */
> @@ -481,8 +635,9 @@ static void atmel_stop_tx(struct uart_port *port)
>  	/* Disable interrupts */
>  	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
>  
> -	if ((port->rs485.flags & SER_RS485_ENABLED) &&
> -	    !(port->rs485.flags & SER_RS485_RX_DURING_TX))
> +	if (((port->rs485.flags & SER_RS485_ENABLED) &&
> +	     !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
> +	    port->iso7816.flags & SER_ISO7816_ENABLED)
>  		atmel_start_rx(port);
>  }
>  
> @@ -500,8 +655,9 @@ static void atmel_start_tx(struct uart_port *port)
>  		return;
>  
>  	if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port))
> -		if ((port->rs485.flags & SER_RS485_ENABLED) &&
> -		    !(port->rs485.flags & SER_RS485_RX_DURING_TX))
> +		if (((port->rs485.flags & SER_RS485_ENABLED) &&
> +		     !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
> +		    port->iso7816.flags & SER_ISO7816_ENABLED)
>  			atmel_stop_rx(port);
>  
>  	if (atmel_use_pdc_tx(port))
> @@ -799,8 +955,9 @@ static void atmel_complete_tx_dma(void *arg)
>  	 */
>  	if (!uart_circ_empty(xmit))
>  		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
> -	else if ((port->rs485.flags & SER_RS485_ENABLED) &&
> -		 !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
> +	else if (((port->rs485.flags & SER_RS485_ENABLED) &&
> +		  !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
> +		 port->iso7816.flags & SER_ISO7816_ENABLED) {
>  		/* DMA done, stop TX, start RX for RS485 */
>  		atmel_start_rx(port);
>  	}
> @@ -1281,6 +1438,9 @@ atmel_handle_status(struct uart_port *port, unsigned int pending,
>  			wake_up_interruptible(&port->state->port.delta_msr_wait);
>  		}
>  	}
> +
> +	if (pending & (ATMEL_US_NACK | ATMEL_US_ITERATION))
> +		dev_dbg(port->dev, "ISO7816 ERROR (0x%08x)\n", pending);
>  }
>  
>  /*
> @@ -1373,8 +1533,9 @@ static void atmel_tx_pdc(struct uart_port *port)
>  		atmel_uart_writel(port, ATMEL_US_IER,
>  				  atmel_port->tx_done_mask);
>  	} else {
> -		if ((port->rs485.flags & SER_RS485_ENABLED) &&
> -		    !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
> +		if (((port->rs485.flags & SER_RS485_ENABLED) &&
> +		     !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
> +		    port->iso7816.flags & SER_ISO7816_ENABLED) {
>  			/* DMA done, stop TX, start RX for RS485 */
>  			atmel_start_rx(port);
>  		}
> @@ -2099,6 +2260,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
>  		atmel_uart_writel(port, ATMEL_US_TTGR,
>  				  port->rs485.delay_rts_after_send);
>  		mode |= ATMEL_US_USMODE_RS485;
> +	} else if (port->iso7816.flags & SER_ISO7816_ENABLED) {
> +		atmel_uart_writel(port, ATMEL_US_TTGR, port->iso7816.tg);
> +		/* select mck clock, and output  */
> +		mode |= ATMEL_US_USCLKS_MCK | ATMEL_US_CLKO;
> +		/* set max iterations */
> +		mode |= ATMEL_US_MAX_ITER(3);
> +		if ((port->iso7816.flags & SER_ISO7816_T_PARAM)
> +				== SER_ISO7816_T(0))
> +			mode |= ATMEL_US_USMODE_ISO7816_T0;
> +		else
> +			mode |= ATMEL_US_USMODE_ISO7816_T1;
>  	} else if (termios->c_cflag & CRTSCTS) {
>  		/* RS232 with hardware handshake (RTS/CTS) */
>  		if (atmel_use_fifo(port) &&
> @@ -2175,7 +2347,8 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
>  	}
>  	quot = cd | fp << ATMEL_US_FP_OFFSET;
>  
> -	atmel_uart_writel(port, ATMEL_US_BRGR, quot);
> +	if (!(port->iso7816.flags & SER_ISO7816_ENABLED))
> +		atmel_uart_writel(port, ATMEL_US_BRGR, quot);
>  	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
>  	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);
>  	atmel_port->tx_stopped = false;
> @@ -2355,6 +2528,7 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
>  	port->mapbase	= pdev->resource[0].start;
>  	port->irq	= pdev->resource[1].start;
>  	port->rs485_config	= atmel_config_rs485;
> +	port->iso7816_config	= atmel_config_iso7816;
>  	port->membase	= NULL;
>  
>  	memset(&atmel_port->rx_ring, 0, sizeof(atmel_port->rx_ring));
> @@ -2378,8 +2552,12 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
>  		/* only enable clock when USART is in use */
>  	}
>  
> -	/* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
> -	if (port->rs485.flags & SER_RS485_ENABLED)
> +	/*
> +	 * Use TXEMPTY for interrupt when rs485 or ISO7816 else TXRDY or
> +	 * ENDTX|TXBUFE
> +	 */
> +	if (port->rs485.flags & SER_RS485_ENABLED ||
> +	    port->iso7816.flags & SER_ISO7816_ENABLED)
>  		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
>  	else if (atmel_use_pdc_tx(port)) {
>  		port->fifosize = PDC_BUFFER_SIZE;
> @@ -2719,6 +2897,11 @@ static int atmel_serial_probe(struct platform_device *pdev)
>  	}
>  
>  	atmel_port = &atmel_ports[ret];
> +	atmel_port->pdata = of_device_get_match_data(&pdev->dev);
> +	if (!atmel_port->pdata) {
> +		ret = -EINVAL;
> +		goto err;
> +	}
>  	atmel_port->backup_imr = 0;
>  	atmel_port->uart.line = ret;
>  	atmel_serial_probe_fifos(atmel_port, pdev);
> diff --git a/drivers/tty/serial/atmel_serial.h b/drivers/tty/serial/atmel_serial.h
> index ba3a2437cde4..6911177964ad 100644
> --- a/drivers/tty/serial/atmel_serial.h
> +++ b/drivers/tty/serial/atmel_serial.h
> @@ -78,7 +78,8 @@
>  #define	ATMEL_US_OVER		BIT(19)	/* Oversampling Mode */
>  #define	ATMEL_US_INACK		BIT(20)	/* Inhibit Non Acknowledge */
>  #define	ATMEL_US_DSNACK		BIT(21)	/* Disable Successive NACK */
> -#define	ATMEL_US_MAX_ITER	GENMASK(26, 24)	/* Max Iterations */
> +#define	ATMEL_US_MAX_ITER_MASK	GENMASK(26, 24)	/* Max Iterations */
> +#define	ATMEL_US_MAX_ITER(n)	(((n) << 24) & ATMEL_US_MAX_ITER_MASK)
>  #define	ATMEL_US_FILTER		BIT(28)	/* Infrared Receive Line Filter */
>  
>  #define ATMEL_US_IER		0x08	/* Interrupt Enable Register */
> @@ -124,7 +125,8 @@
>  #define ATMEL_US_TTGR		0x28	/* Transmitter Timeguard Register */
>  #define	ATMEL_US_TG		GENMASK(7, 0)	/* Timeguard Value */
>  
> -#define ATMEL_US_FIDI		0x40	/* FI DI Ratio Register */
> +#define ATMEL_US_FIDIR		0x40	/* FI DI Ratio Register */
> +#define ATMEL_US_FIDI		GENMASK(15, 0)	/* FIDI ratio */
>  #define ATMEL_US_NER		0x44	/* Number of Errors Register */
>  #define ATMEL_US_IF		0x4c	/* IrDA Filter Register */
>  
> 
Thanks !