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Mon, 16 Sep 2019 00:10:26 -0700 Received: from saturn.ad.analog.com (10.48.65.123) by NWD2HUBCAS7.ad.analog.com (10.64.69.107) with Microsoft SMTP Server id 14.3.408.0; Mon, 16 Sep 2019 03:10:31 -0400 From: Alexandru Ardelean To: , , CC: , , Alexandru Ardelean Subject: [PATCH v3 2/3] spi: introduce spi_delay struct as "value + unit" & spi_delay_exec() Date: Mon, 16 Sep 2019 10:10:23 +0300 Message-ID: <20190916071024.21447-3-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190916071024.21447-1-alexandru.ardelean@analog.com> References: <20190916071024.21447-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 X-ADIRoutedOnPrem: True X-EOPAttributedMessage: 0 X-MS-Office365-Filtering-HT: Tenant X-Forefront-Antispam-Report: CIP:137.71.25.57;IPV:NLI;CTRY:US;EFV:NLI;SFV:NSPM;SFS:(10009020)(376002)(346002)(136003)(39860400002)(396003)(199004)(189003)(2616005)(107886003)(478600001)(246002)(50466002)(106002)(426003)(186003)(36756003)(2201001)(110136005)(486006)(44832011)(26005)(48376002)(316002)(7636002)(54906003)(305945005)(446003)(47776003)(50226002)(7696005)(356004)(2906002)(70586007)(70206006)(476003)(51416003)(8676002)(5660300002)(2870700001)(126002)(336012)(76176011)(14444005)(6666004)(86362001)(1076003)(4326008)(11346002)(8936002);DIR:OUT;SFP:1101;SCL:1;SRVR:MWHPR03MB2575;H:nwd2mta2.analog.com;FPR:;SPF:Pass;LANG:en;PTR:nwd2mail11.analog.com;A:1;MX:1; X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 007c9fdb-0def-4145-c188-08d73a74f61e X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(5600167)(711020)(4605104)(4709080)(1401327)(4618075)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(2017052603328);SRVR:MWHPR03MB2575; X-MS-TrafficTypeDiagnostic: MWHPR03MB2575: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:7219; X-Forefront-PRVS: 0162ACCC24 X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam-Message-Info: cJ3ZfMhwlRk9gX6zUcX2rPod4tvASTFPgxz+UN+WYJw+I8ubwzu5ETVxgE55/iqfGtJlHsWrzYZlAAqASGplGiKr/0mySKAWrxjF6x3aj0GqqeSZ2uWIoyiK+yhB6PPZxLsR2baMfy1kWMXcPbK2y4MNAnf+EztG3I/Es3i6k+kNQ3iDSWIiXhiRKCP7cPgROahC5Oh8Dor1aMmE8alr0DdU0BjCWC9ia1i1ZALbbHqDztMfVV9Ud83QP9l2ZJyZWuur/Or18J2cg2PVJ/F3u2ep4ETD7qHgohzkw09rJpSxRkkkd4OTCIDILYc0NIBfcABMR7csMYElUOePN7ydQf+7z6joUiKXCESLgknsmopN3F4Wrx1XC6eqb+PiHS2DSe00IaU+ON03mvsV2LnFj8VC+TmHDJ8RQUuBk9FkrP8= X-OriginatorOrg: analog.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Sep 2019 07:10:31.5622 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 007c9fdb-0def-4145-c188-08d73a74f61e X-MS-Exchange-CrossTenant-Id: eaa689b4-8f87-40e0-9c6f-7228de4d754a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=eaa689b4-8f87-40e0-9c6f-7228de4d754a;Ip=[137.71.25.57];Helo=[nwd2mta2.analog.com] X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR03MB2575 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.70,1.0.8 definitions=2019-09-16_04:2019-09-11,2019-09-16 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 spamscore=0 suspectscore=0 mlxlogscore=999 bulkscore=0 mlxscore=0 priorityscore=1501 clxscore=1015 malwarescore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1908290000 definitions=main-1909160077 Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org There are plenty of delays that have been introduced in SPI core. Most of them are in micro-seconds, some need to be in nano-seconds, and some in clock-cycles. For some of these delays (related to transfers & CS timing) it may make sense to have a `spi_delay` struct that abstracts these a bit. The important element of these delays [for unification] seems to be the `unit` of the delay. It looks like micro-seconds is good enough for most people, but every-once in a while, some delays seem to require other units of measurement. This change adds the `spi_delay` struct & a `spi_delay_exec()` function that processes a `spi_delay` object/struct to execute the delay. It's a copy of the `cs_change_delay` mechanism, but without the default for 10 uS. The clock-cycle delay unit is a bit special, as it needs to be bound to an `spi_transfer` object to execute. Signed-off-by: Alexandru Ardelean --- drivers/spi/spi.c | 51 +++++++++++++++++++++++++++++++++++++++++ include/linux/spi/spi.h | 18 ++++++++++++--- 2 files changed, 66 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index c90e02e6d62f..1883de8ffa82 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1106,6 +1106,57 @@ static void _spi_transfer_delay_ns(u32 ns) } } +static int _spi_delay_to_ns(struct spi_delay *_delay, struct spi_transfer *xfer) +{ + u32 delay = _delay->value; + u32 unit = _delay->unit; + u32 hz; + + if (!delay) + return 0; + + switch (unit) { + case SPI_DELAY_UNIT_USECS: + delay *= 1000; + break; + case SPI_DELAY_UNIT_NSECS: /* nothing to do here */ + break; + case SPI_DELAY_UNIT_SCK: + /* clock cycles need to be obtained from spi_transfer */ + if (!xfer) + return -EINVAL; + /* if there is no effective speed know, then approximate + * by underestimating with half the requested hz + */ + hz = xfer->effective_speed_hz ?: xfer->speed_hz / 2; + if (!hz) + return -EINVAL; + delay *= DIV_ROUND_UP(1000000000, hz); + break; + default: + return -EINVAL; + } + + return delay; +} + +int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer) +{ + int delay; + + if (!_delay) + return -EINVAL; + + delay = _spi_delay_to_ns(_delay, xfer); + if (delay < 0) + return delay; + + _spi_transfer_delay_ns(delay); + + return 0; +} +EXPORT_SYMBOL_GPL(spi_delay_exec); + static void _spi_transfer_cs_change_delay(struct spi_message *msg, struct spi_transfer *xfer) { diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index af4f265d0f67..c18cfa7cda35 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -89,6 +89,21 @@ void spi_statistics_add_transfer_stats(struct spi_statistics *stats, #define SPI_STATISTICS_INCREMENT_FIELD(stats, field) \ SPI_STATISTICS_ADD_TO_FIELD(stats, field, 1) +/** + * struct spi_delay - SPI delay information + * @value: Value for the delay + * @unit: Unit for the delay + */ +struct spi_delay { +#define SPI_DELAY_UNIT_USECS 0 +#define SPI_DELAY_UNIT_NSECS 1 +#define SPI_DELAY_UNIT_SCK 2 + u16 value; + u8 unit; +}; + +extern int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer); + /** * struct spi_device - Controller side proxy for an SPI slave device * @dev: Driver model representation of the device. @@ -834,9 +849,6 @@ struct spi_transfer { u16 delay_usecs; u16 cs_change_delay; u8 cs_change_delay_unit; -#define SPI_DELAY_UNIT_USECS 0 -#define SPI_DELAY_UNIT_NSECS 1 -#define SPI_DELAY_UNIT_SCK 2 u32 speed_hz; u16 word_delay;