linux-kernel - Re: [RESEND PATCH 1/1] can: m_can: fix bitrate setup on latest silicon

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Date:   Mon, 20 Feb 2017 17:50:01 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Quentin Schulz <quentin.schulz@...e-electrons.com>,
        wg@...ndegger.com, fvallee@...rea.fr
Cc:     linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, boris.brezillon@...e-electrons.com,
        alexandre.belloni@...e-electrons.com, nicolas.ferre@...el.com
Subject: Re: [RESEND PATCH 1/1] can: m_can: fix bitrate setup on latest
 silicon

On 02/15/2017 03:08 PM, Quentin Schulz wrote:
> From: Florian Vallee <fvallee@...rea.fr>
> 
> According to the m_can user manual changelog the BTP register layout was
> updated with core revision 3.1.0
> 
> This change is not backward-compatible and using the current driver along
> with a recent IP results in an incorrect bitrate on the wire.
> 
> Tested with a SAMA5D2 SoC (CREL = 0x31040730)
> 
> Signed-off-by: Florian Vallee <fvallee@...rea.fr>
> Tested-by: Quentin Schulz <quentin.schulz@...e-electrons.com>

Can you please add your S-o-b here, too.

> ---
>  drivers/net/can/m_can/m_can.c | 38 +++++++++++++++++++++++++++++++++++---
>  1 file changed, 35 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 195f15e..246584e 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -105,6 +105,10 @@ enum m_can_mram_cfg {
>  	MRAM_CFG_NUM,
>  };
>  
> +/* Core Release Register (CREL) */
> +#define CRR_REL_MASK		0xfff
> +#define CRR_REL_SHIFT		20
> +
>  /* Fast Bit Timing & Prescaler Register (FBTP) */
>  #define FBTR_FBRP_MASK		0x1f
>  #define FBTR_FBRP_SHIFT		16
> @@ -136,7 +140,7 @@ enum m_can_mram_cfg {
>  #define CCCR_INIT		BIT(0)
>  #define CCCR_CANFD		0x10
>  
> -/* Bit Timing & Prescaler Register (BTP) */
> +/* Bit Timing & Prescaler Register (BTP) (M_CAN IP < 3.1.0) */
>  #define BTR_BRP_MASK		0x3ff
>  #define BTR_BRP_SHIFT		16
>  #define BTR_TSEG1_SHIFT		8
> @@ -146,6 +150,16 @@ enum m_can_mram_cfg {
>  #define BTR_SJW_SHIFT		0
>  #define BTR_SJW_MASK		0xf
>  
> +/* Nominal Bit Timing & Prescaler Register (NBTP) (M_CAN IP >= 3.1.0) */
> +#define NBTR_SJW_SHIFT		25
> +#define NBTR_SJW_MASK		(0x7f << NBTR_SJW_SHIFT)
> +#define NBTR_BRP_SHIFT		16
> +#define NBTR_BRP_MASK		(0x3ff << NBTR_BRP_SHIFT)
> +#define NBTR_TSEG1_SHIFT	8
> +#define NBTR_TSEG1_MASK		(0xff << NBTR_TSEG1_SHIFT)
> +#define NBTR_TSEG2_SHIFT	0
> +#define NBTR_TSEG2_MASK		(0x7f << NBTR_TSEG2_SHIFT)

Use BTR_310_ as a prefix here.

> +
>  /* Error Counter Register(ECR) */
>  #define ECR_RP			BIT(15)
>  #define ECR_REC_SHIFT		8
> @@ -200,6 +214,9 @@ enum m_can_mram_cfg {
>  			 IR_RF1L | IR_RF0L)
>  #define IR_ERR_ALL	(IR_ERR_STATE | IR_ERR_BUS)
>  
> +/* Core Version */
> +#define M_CAN_COREREL_3_1_0	0x310

_310 should be fine

> +
>  /* Interrupt Line Select (ILS) */
>  #define ILS_ALL_INT0	0x0
>  #define ILS_ALL_INT1	0xFFFFFFFF
> @@ -357,6 +374,13 @@ static inline void m_can_disable_all_interrupts(const struct m_can_priv *priv)
>  	m_can_write(priv, M_CAN_ILE, 0x0);
>  }
>  
> +static inline int m_can_read_core_rev(const struct m_can_priv *priv)

make it an u16

> +{
> +	u32 reg = m_can_read(priv, M_CAN_CREL);
> +
> +	return ((reg >> CRR_REL_SHIFT) & CRR_REL_MASK);
> +}
> +
>  static void m_can_read_fifo(struct net_device *dev, u32 rxfs)
>  {
>  	struct net_device_stats *stats = &dev->stats;
> @@ -811,8 +835,16 @@ static int m_can_set_bittiming(struct net_device *dev)
>  	sjw = bt->sjw - 1;
>  	tseg1 = bt->prop_seg + bt->phase_seg1 - 1;
>  	tseg2 = bt->phase_seg2 - 1;
> -	reg_btp = (brp << BTR_BRP_SHIFT) | (sjw << BTR_SJW_SHIFT) |
> -			(tseg1 << BTR_TSEG1_SHIFT) | (tseg2 << BTR_TSEG2_SHIFT);
> +
> +	if (m_can_read_core_rev(priv) < M_CAN_COREREL_3_1_0)
> +		reg_btp = (brp << BTR_BRP_SHIFT) | (sjw << BTR_SJW_SHIFT) |
> +				(tseg1 << BTR_TSEG1_SHIFT) |
> +				(tseg2 << BTR_TSEG2_SHIFT);
> +	else
> +		reg_btp = (brp << NBTR_BRP_SHIFT) | (sjw << NBTR_SJW_SHIFT) |
> +				(tseg1 << NBTR_TSEG1_SHIFT) |
> +				(tseg2 << NBTR_TSEG2_SHIFT);
> +
>  	m_can_write(priv, M_CAN_BTP, reg_btp);
>  
>  	if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
> 

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
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