iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted

vl53l0x_read_raw() starts a single-shot ranging measurement and reads
back the result. Once the triggered buffer is enabled the sensor runs in
continuous mode and its data-ready interrupt is routed to the trigger,
so a concurrent in_distance_raw read disturbs the streaming setup and
never gets its completion, returning -ETIMEDOUT.

The original submission claimed direct mode here, but it was dropped
during review because the driver had no buffer support at the time [1].
Continuous (buffered) mode was later added without restoring the
claim [2], reintroducing the conflict.

Reject direct reads while buffered capture is active by claiming direct
mode around the measurement, as the vl53l1x sibling already does.

Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support")
Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1]
Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2]
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 218 insertions, 0 deletions

diff --git a/drivers/mtd/maps/plat-ram.c b/drivers/mtd/maps/plat-ram.c
new file mode 100644
index 000000000..816111031
--- /dev/null
+++ b/drivers/mtd/maps/plat-ram.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* drivers/mtd/maps/plat-ram.c
+ *
+ * (c) 2004-2005 Simtec Electronics
+ *	http://www.simtec.co.uk/products/SWLINUX/
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * Generic platform device based RAM map
+*/
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/ioport.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/map.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/plat-ram.h>
+
+#include <asm/io.h>
+
+/* private structure for each mtd platform ram device created */
+
+struct platram_info {
+	struct device		*dev;
+	struct mtd_info		*mtd;
+	struct map_info		 map;
+	struct platdata_mtd_ram	*pdata;
+};
+
+/* to_platram_info()
+ *
+ * device private data to struct platram_info conversion
+*/
+
+static inline struct platram_info *to_platram_info(struct platform_device *dev)
+{
+	return platform_get_drvdata(dev);
+}
+
+/* platram_setrw
+ *
+ * call the platform device's set rw/ro control
+ *
+ * to = 0 => read-only
+ *    = 1 => read-write
+*/
+
+static inline void platram_setrw(struct platram_info *info, int to)
+{
+	if (info->pdata == NULL)
+		return;
+
+	if (info->pdata->set_rw != NULL)
+		(info->pdata->set_rw)(info->dev, to);
+}
+
+/* platram_remove
+ *
+ * called to remove the device from the driver's control
+*/
+
+static void platram_remove(struct platform_device *pdev)
+{
+	struct platram_info *info = to_platram_info(pdev);
+
+	dev_dbg(&pdev->dev, "removing device\n");
+
+	if (info == NULL)
+		return;
+
+	if (info->mtd) {
+		mtd_device_unregister(info->mtd);
+		map_destroy(info->mtd);
+	}
+
+	/* ensure ram is left read-only */
+
+	platram_setrw(info, PLATRAM_RO);
+
+	kfree(info);
+}
+
+/* platram_probe
+ *
+ * called from device drive system when a device matching our
+ * driver is found.
+*/
+
+static int platram_probe(struct platform_device *pdev)
+{
+	struct platdata_mtd_ram	*pdata;
+	struct platram_info *info;
+	struct resource *res;
+	int err = 0;
+
+	dev_dbg(&pdev->dev, "probe entered\n");
+
+	if (dev_get_platdata(&pdev->dev) == NULL) {
+		dev_err(&pdev->dev, "no platform data supplied\n");
+		err = -ENOENT;
+		goto exit_error;
+	}
+
+	pdata = dev_get_platdata(&pdev->dev);
+
+	info = kzalloc_obj(*info);
+	if (info == NULL) {
+		err = -ENOMEM;
+		goto exit_error;
+	}
+
+	platform_set_drvdata(pdev, info);
+
+	info->dev = &pdev->dev;
+	info->pdata = pdata;
+
+	/* get the resource for the memory mapping */
+	info->map.virt = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(info->map.virt)) {
+		err = PTR_ERR(info->map.virt);
+		goto exit_free;
+	}
+
+	dev_dbg(&pdev->dev, "got platform resource %p (0x%llx)\n", res,
+		(unsigned long long)res->start);
+
+	/* setup map parameters */
+
+	info->map.phys = res->start;
+	info->map.size = resource_size(res);
+	info->map.name = pdata->mapname != NULL ?
+			(char *)pdata->mapname : (char *)pdev->name;
+	info->map.bankwidth = pdata->bankwidth;
+
+	dev_dbg(&pdev->dev, "virt %p, %lu bytes\n", info->map.virt, info->map.size);
+
+	simple_map_init(&info->map);
+
+	dev_dbg(&pdev->dev, "initialised map, probing for mtd\n");
+
+	/* probe for the right mtd map driver
+	 * supplied by the platform_data struct */
+
+	if (pdata->map_probes) {
+		const char * const *map_probes = pdata->map_probes;
+
+		for ( ; !info->mtd && *map_probes; map_probes++)
+			info->mtd = do_map_probe(*map_probes , &info->map);
+	}
+	/* fallback to map_ram */
+	else
+		info->mtd = do_map_probe("map_ram", &info->map);
+
+	if (info->mtd == NULL) {
+		dev_err(&pdev->dev, "failed to probe for map_ram\n");
+		err = -ENOMEM;
+		goto exit_free;
+	}
+
+	info->mtd->dev.parent = &pdev->dev;
+
+	platram_setrw(info, PLATRAM_RW);
+
+	/* check to see if there are any available partitions, or whether
+	 * to add this device whole */
+
+	err = mtd_device_parse_register(info->mtd, pdata->probes, NULL,
+					pdata->partitions,
+					pdata->nr_partitions);
+	if (err) {
+		dev_err(&pdev->dev, "failed to register mtd device\n");
+		goto exit_free;
+	}
+
+	dev_info(&pdev->dev, "registered mtd device\n");
+
+	if (pdata->nr_partitions) {
+		/* add the whole device. */
+		err = mtd_device_register(info->mtd, NULL, 0);
+		if (err) {
+			dev_err(&pdev->dev,
+				"failed to register the entire device\n");
+			goto exit_free;
+		}
+	}
+
+	return 0;
+
+ exit_free:
+	platram_remove(pdev);
+ exit_error:
+	return err;
+}
+
+/* device driver info */
+
+/* work with hotplug and coldplug */
+MODULE_ALIAS("platform:mtd-ram");
+
+static struct platform_driver platram_driver = {
+	.probe		= platram_probe,
+	.remove		= platram_remove,
+	.driver		= {
+		.name	= "mtd-ram",
+	},
+};
+
+module_platform_driver(platram_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
+MODULE_DESCRIPTION("MTD platform RAM map driver");