Re: [PATCH 1/3] can: m_can: add infrastructure for internal timestamps - Marc Kleine-Budde

From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Torin Cooper-Bennun <torin@maxiluxsystems.com>
Cc: linux-can@vger.kernel.org, Pankaj Sharma <pankj.sharma@samsung.com>
Subject: Re: [PATCH 1/3] can: m_can: add infrastructure for internal timestamps
Date: Fri, 5 Mar 2021 22:28:33 +0100	[thread overview]
Message-ID: <20210305212833.vzo3zobpwdoyvroa@pengutronix.de> (raw)
In-Reply-To: <20210305172015.1506525-2-torin@maxiluxsystems.com>

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On 05.03.2021 17:20:13, Torin Cooper-Bennun wrote:
> Add infrastucture to allow internal timestamps from the M_CAN to be
> configured and retrieved.
>
> Signed-off-by: Torin Cooper-Bennun <torin@maxiluxsystems.com>
> ---
>  drivers/net/can/m_can/m_can.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 0c8d36bc668c..ea79cf0640a8 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -148,6 +148,19 @@ enum m_can_reg {
>  #define NBTP_NTSEG2_SHIFT	0
>  #define NBTP_NTSEG2_MASK	(0x7f << NBTP_NTSEG2_SHIFT)
>
> +/* Timestamp Counter Configuration Register (TSCC) */
> +#define TSCC_TCP_SHIFT		16
> +#define TSCC_TCP_MASK		(0xf << TSCC_TCP_SHIFT)
> +#define TSCC_TSS_SHIFT		0
> +#define TSCC_TSS_MASK		(0x3 << TSCC_TSS_SHIFT)
> +#define TSCC_TSS_DISABLE	(0x0 << TSCC_TSS_SHIFT)
> +#define TSCC_TSS_INTERNAL	(0x1 << TSCC_TSS_SHIFT)
> +#define TSCC_TSS_EXTERNAL	(0x2 << TSCC_TSS_SHIFT)

Even if the driver doesn't make use of GENMASK(), please add new masks
with GENMASK(), there's no need to define the _SHIFT values.

> +
> +/* Timestamp Counter Value Register (TSCV) */
> +#define TSCV_TSC_SHIFT		0
> +#define TSCV_TSC_MASK		(0xffff << TSCV_TSC_SHIFT)
> +
>  /* Error Counter Register(ECR) */
>  #define ECR_RP			BIT(15)
>  #define ECR_REC_SHIFT		8
> @@ -302,6 +315,8 @@ enum m_can_reg {
>  #define RX_BUF_ANMF		BIT(31)
>  #define RX_BUF_FDF		BIT(21)
>  #define RX_BUF_BRS		BIT(20)
> +#define RX_BUF_RXTS_SHIFT	0
> +#define RX_BUF_RXTS_MASK	(0xffff << RX_BUF_RXTS_SHIFT)
>
>  /* Tx Buffer Element */
>  /* T0 */
> @@ -319,6 +334,8 @@ enum m_can_reg {
>  /* E1 */
>  #define TX_EVENT_MM_SHIFT	TX_BUF_MM_SHIFT
>  #define TX_EVENT_MM_MASK	(0xff << TX_EVENT_MM_SHIFT)
> +#define TX_EVENT_TXTS_SHIFT	0
> +#define TX_EVENT_TXTS_MASK	(0xffff << TX_EVENT_TXTS_SHIFT)
>
>  static inline u32 m_can_read(struct m_can_classdev *cdev, enum m_can_reg reg)
>  {
> @@ -413,6 +430,20 @@ static inline void m_can_disable_all_interrupts(struct m_can_classdev *cdev)
>  	m_can_write(cdev, M_CAN_ILE, 0x0);
>  }
>
> +/* Retrieve internal timestamp counter from TSCV.TSC, and shift it to 32-bit
> + * width.
> + */
> +static u32 m_can_get_timestamp(struct m_can_classdev *cdev)
> +{
> +	u32 tscv;
> +	u32 tsc;
> +
> +	tscv = m_can_read(cdev, M_CAN_TSCV);
> +	tsc = (tscv & TSCV_TSC_MASK) >> TSCV_TSC_SHIFT;

Make use of FIELD_GET here:

     tsc = FIELD_GET(TSCV_TSC_MASK, tcsv);

Marc

--
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
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