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Received: from nwd2mta2.analog.com (137.71.25.57) by SN1NAM02FT048.mail.protection.outlook.com (10.152.72.202) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.20.2241.14 via Frontend Transport; Fri, 13 Sep 2019 08:46:15 +0000 Received: from NWD2HUBCAS7.ad.analog.com (nwd2hubcas7.ad.analog.com [10.64.69.107]) by nwd2mta2.analog.com (8.13.8/8.13.8) with ESMTP id x8D8kAVv030611 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=OK); Fri, 13 Sep 2019 01:46:10 -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; Fri, 13 Sep 2019 04:46:14 -0400 From: Alexandru Ardelean To: , , , , , CC: , , , , , , , Alexandru Ardelean Subject: [RFC PATCH 02/15] spi: introduce spi_delay struct as "value + unit" & spi_delay_exec() Date: Fri, 13 Sep 2019 14:45:37 +0300 Message-ID: <20190913114550.956-3-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190913114550.956-1-alexandru.ardelean@analog.com> References: <20190913114550.956-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain 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)(346002)(396003)(136003)(376002)(39860400002)(199004)(189003)(2201001)(426003)(7696005)(51416003)(14444005)(316002)(110136005)(76176011)(54906003)(2906002)(8936002)(50226002)(70586007)(70206006)(44832011)(486006)(36756003)(2870700001)(7416002)(86362001)(26005)(336012)(106002)(186003)(305945005)(11346002)(2616005)(107886003)(446003)(47776003)(1076003)(478600001)(126002)(356004)(246002)(8676002)(6666004)(48376002)(50466002)(5660300002)(4326008)(7636002)(476003)(2101003);DIR:OUT;SFP:1101;SCL:1;SRVR:SN6PR03MB3806;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: 714ced24-9e3c-4869-8f80-08d73826d68a X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600166)(711020)(4605104)(4709080)(1401327)(4618075)(2017052603328);SRVR:SN6PR03MB3806; X-MS-TrafficTypeDiagnostic: SN6PR03MB3806: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:7219; X-Forefront-PRVS: 0159AC2B97 X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam-Message-Info: 6l1XnoKGWXWzCRMQEDiQUrubWL+RBbwWA2jZj9vXXHZJ18ROjphPn6ez7YmTvsTwddYY5FQ18eeMwPRAtGq+utZIroj+GPoWRXUVFX8aVh7QJuOCIBQMB7jAUl1uuiKarbna3+325l5qHQt57FFxTFW7R6QqeqvmNtYEYBTZCCH1rxaRKskSV7vN5gZCYOvAmtnREDuWVWjyJl5ohxqn+AKVS1hLpJNpOjggT2pJ5UaSIUrEYUVEILv/Rh9wRMAuDa/MyjrKfkECdevNcq4N9kYWDILYZ/CmE1+xPJ3oCyhhobxNtKrqJc17NELoVNY/+L58PX2KA3vQjxyxS0moT4QLVOOmUnL/stNLu49L/Y0acpjKiy7IB70EMjhJaIWld68XnoWyriJ/3WvmIJjuJZzBDIdZtG5pQu0X3zirCAY= X-OriginatorOrg: analog.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Sep 2019 08:46:15.4301 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 714ced24-9e3c-4869-8f80-08d73826d68a 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: SN6PR03MB3806 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.70,1.0.8 definitions=2019-09-13_05:2019-09-11,2019-09-13 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 impostorscore=0 priorityscore=1501 suspectscore=0 clxscore=1015 lowpriorityscore=0 malwarescore=0 spamscore=0 adultscore=0 mlxscore=0 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1908290000 definitions=main-1909130083 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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; -- 2.20.1