Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Received-SPF: Pass (protection.outlook.com: domain of amd.com designates
 165.204.84.17 as permitted sender) receiver=protection.outlook.com;
 client-ip=165.204.84.17; helo=SATLEXMB03.amd.com; pr=C
From:   Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
To:     Tudor Ambarus <tudor.ambarus@microchip.com>,
        Pratyush Yadav <pratyush@kernel.org>,
        Michael Walle <michael@walle.cc>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        "Vignesh Raghavendra" <vigneshr@ti.com>,
        Rob Herring <robh+dt@kernel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>
CC:     <devicetree@vger.kernel.org>, <linux-mtd@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <saikrishna12468@gmail.com>,
        <git@amd.com>, Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
Subject: [PATCH v3 2/2] mtd: spi-nor: Add support for flash reset
Date:   Thu, 8 Sep 2022 12:14:28 +0530
Message-ID: <20220908064428.2962-3-sai.krishna.potthuri@amd.com>
In-Reply-To: <20220908064428.2962-1-sai.krishna.potthuri@amd.com>
References: <20220908064428.2962-1-sai.krishna.potthuri@amd.com>
MIME-Version: 1.0
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Sep 2022 06:47:25.5721
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 28b5fdb2-1992-42f1-a424-08da9165fd87
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB03.amd.com]
X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT049.eop-nam11.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO6PR12MB5475
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE
        autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Add support for spi-nor flash reset via GPIO controller by reading the
reset-gpio property. If there is a valid GPIO specifier then reset will
be performed by asserting and deasserting the GPIO using gpiod APIs
otherwise it will not perform any operation.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
Reviewed-by: Michael Walle <michael@walle.cc>
---
 drivers/mtd/spi-nor/core.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index f2c64006f8d7..a78ab9bae2be 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2933,6 +2933,27 @@ static void spi_nor_set_mtd_info(struct spi_nor *nor)
 	mtd->_put_device = spi_nor_put_device;
 }
 
+static int spi_nor_hw_reset(struct spi_nor *nor)
+{
+	struct gpio_desc *reset;
+
+	reset = devm_gpiod_get_optional(nor->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR_OR_NULL(reset))
+		return PTR_ERR_OR_ZERO(reset);
+
+	/*
+	 * Experimental delay values by looking at different flash device
+	 * vendors datasheets.
+	 */
+	usleep_range(1, 5);
+	gpiod_set_value_cansleep(reset, 1);
+	usleep_range(100, 150);
+	gpiod_set_value_cansleep(reset, 0);
+	usleep_range(1000, 1200);
+
+	return 0;
+}
+
 int spi_nor_scan(struct spi_nor *nor, const char *name,
 		 const struct spi_nor_hwcaps *hwcaps)
 {
@@ -2965,6 +2986,10 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	if (!nor->bouncebuf)
 		return -ENOMEM;
 
+	ret = spi_nor_hw_reset(nor);
+	if (ret)
+		return ret;
+
 	info = spi_nor_get_flash_info(nor, name);
 	if (IS_ERR(info))
 		return PTR_ERR(info);
-- 
2.17.1