linux-kernel - [RFC PATCH 5/8] mtd: rawnand: ams-delta: Request data port GPIO resource

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Date:   Thu, 19 Jul 2018 01:57:07 +0200
From:   Janusz Krzysztofik <jmkrzyszt@...il.com>
To:     Boris Brezillon <boris.brezillon@...tlin.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Tony Lindgren <tony@...mide.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
        Janusz Krzysztofik <jmkrzyszt@...il.com>
Subject: [RFC PATCH 5/8] mtd: rawnand: ams-delta: Request data port GPIO resource

Data port used by the driver is actually an OMAP MPUIO device, already
under control of gpio-omap driver.  For that reason we used to not
request the memory region of the port as that would fail because the
region is already busy.  Despite that, we are still accessing the port
by just ioremapping it and performing read/write operations.  Moreover,
we are doing that without any proteciton from other users legally
manipulating the port pins over GPIO API.

The plan is to convert the driver to access the port over functions
exposed by the gpio-omap driver.  Before that happens, we can already
obtain exclusive access to the port by requesting an array of its GPIO
descriptors.  For that to work on Amstrad Delta, respective GPIO lookup
table entries are added to the board init file.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@...il.com>
---
 arch/arm/mach-omap1/board-ams-delta.c | 11 ++++++++++-
 drivers/mtd/nand/raw/ams-delta.c      |  8 ++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-omap1/board-ams-delta.c b/arch/arm/mach-omap1/board-ams-delta.c
index eedacdfe9725..16f7bbe47607 100644
--- a/arch/arm/mach-omap1/board-ams-delta.c
+++ b/arch/arm/mach-omap1/board-ams-delta.c
@@ -337,7 +337,8 @@ static struct platform_device ams_delta_nand_device = {
 	.resource	= ams_delta_nand_resources,
 };
 
-#define OMAP_GPIO_LABEL	"gpio-0-15"
+#define OMAP_GPIO_LABEL		"gpio-0-15"
+#define OMAP_MPUIO_LABEL	"mpuio"
 
 static struct gpiod_lookup_table ams_delta_nand_gpio_table = {
 	.table = {
@@ -349,6 +350,14 @@ static struct gpiod_lookup_table ams_delta_nand_gpio_table = {
 		GPIO_LOOKUP(LATCH2_LABEL, LATCH2_PIN_NAND_NWE, "nwe", 0),
 		GPIO_LOOKUP(LATCH2_LABEL, LATCH2_PIN_NAND_ALE, "ale", 0),
 		GPIO_LOOKUP(LATCH2_LABEL, LATCH2_PIN_NAND_CLE, "cle", 0),
+		GPIO_LOOKUP_IDX(OMAP_MPUIO_LABEL, 0, "data", 0, 0),
+		GPIO_LOOKUP_IDX(OMAP_MPUIO_LABEL, 1, "data", 1, 0),
+		GPIO_LOOKUP_IDX(OMAP_MPUIO_LABEL, 2, "data", 2, 0),
+		GPIO_LOOKUP_IDX(OMAP_MPUIO_LABEL, 3, "data", 3, 0),
+		GPIO_LOOKUP_IDX(OMAP_MPUIO_LABEL, 4, "data", 4, 0),
+		GPIO_LOOKUP_IDX(OMAP_MPUIO_LABEL, 5, "data", 5, 0),
+		GPIO_LOOKUP_IDX(OMAP_MPUIO_LABEL, 6, "data", 6, 0),
+		GPIO_LOOKUP_IDX(OMAP_MPUIO_LABEL, 7, "data", 7, 0),
 		{ },
 	},
 };
diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
index d7e4c9dbef67..ad62c0245458 100644
--- a/drivers/mtd/nand/raw/ams-delta.c
+++ b/drivers/mtd/nand/raw/ams-delta.c
@@ -189,6 +189,7 @@ static int ams_delta_init(struct platform_device *pdev)
 	struct mtd_info *mtd;
 	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	void __iomem *io_base;
+	struct gpio_descs *data_gpiods;
 	int err = 0;
 
 	if (!res)
@@ -289,6 +290,13 @@ static int ams_delta_init(struct platform_device *pdev)
 		dev_err(&pdev->dev, "CLE GPIO request failed (%d)\n", err);
 		goto out_mtd;
 	}
+	/* Request array of data pins, initialize them as output and set low */
+	data_gpiods = devm_gpiod_get_array(&pdev->dev, "data", GPIOD_OUT_LOW);
+	if (IS_ERR(data_gpiods)) {
+		err = PTR_ERR(data_gpiods);
+		dev_err(&pdev->dev, "data GPIO request failed: %d\n", err);
+		goto out_mtd;
+	}
 
 	/* Scan to find existence of the device */
 	err = nand_scan(mtd, 1);
-- 
2.16.4