[RFC PATCH 6/9] drm/i915/spi: spi register with mtd

[Tomas Winkler]

Register the on-die spi device with the mtd subsystem.
Add mtd access stub functions.

Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler at intel.com>
---
 drivers/gpu/drm/i915/spi/intel_spi_drv.c | 86 +++++++++++++++++++++++-
 1 file changed, 85 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/spi/intel_spi_drv.c b/drivers/gpu/drm/i915/spi/intel_spi_drv.c
index df6a461d520d..bdf58e14fd6b 100644
--- a/drivers/gpu/drm/i915/spi/intel_spi_drv.c
+++ b/drivers/gpu/drm/i915/spi/intel_spi_drv.c
@@ -15,7 +15,11 @@
 #include <linux/delay.h>
 #include <spi/intel_spi.h>
 
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+
 struct i915_spi {
+	struct mtd_info mtd;
 	void __iomem *base;
 	size_t size;
 	unsigned int nregions;
@@ -344,6 +348,73 @@ static int i915_spi_init(struct i915_spi *spi, struct device *device)
 	return n;
 }
 
+static int i915_spi_erase(struct mtd_info *mtd, struct erase_info *info)
+{
+	dev_err(&mtd->dev, "erasing %lld %lld\n", info->addr, info->len);
+
+	return 0;
+}
+
+static int i915_spi_read(struct mtd_info *mtd, loff_t from, size_t len,
+			 size_t *retlen, u_char *buf)
+{
+	dev_err(&mtd->dev, "read %lld %zd\n", from, len);
+
+	return 0;
+}
+
+static int i915_spi_write(struct mtd_info *mtd, loff_t to, size_t len,
+			  size_t *retlen, const u_char *buf)
+{
+	dev_err(&mtd->dev, "writing %lld %zd\n", to, len);
+
+	return 0;
+}
+
+static int i915_spi_init_mtd(struct i915_spi *spi, struct device *device,
+			     unsigned int nparts)
+{
+	unsigned int i;
+	unsigned int n;
+	struct mtd_partition *parts = NULL;
+	int ret;
+
+	dev_dbg(device, "registering with mtd\n");
+
+	spi->mtd.owner = THIS_MODULE;
+	spi->mtd.dev.parent = device;
+	spi->mtd.flags = MTD_CAP_NORFLASH | MTD_WRITEABLE;
+	spi->mtd.type = MTD_DATAFLASH;
+	spi->mtd.priv = spi;
+	spi->mtd._write = i915_spi_write;
+	spi->mtd._read = i915_spi_read;
+	spi->mtd._erase = i915_spi_erase;
+	spi->mtd.writesize = SZ_4; /* 4 bytes granularity */
+	spi->mtd.erasesize = SZ_4K; /* 4K bytes granularity */
+	spi->mtd.size = spi->size;
+
+	parts = kcalloc(spi->nregions, sizeof(*parts), GFP_KERNEL);
+	if (!parts)
+		return -ENOMEM;
+
+	for (i = 0, n = 0; i < spi->nregions && n < nparts; i++) {
+		if (!spi->regions[i].is_readable)
+			continue;
+		parts[n].name = spi->regions[i].name;
+		parts[n].offset  = spi->regions[i].offset;
+		parts[n].size = spi->regions[i].size;
+		if (!spi->regions[i].is_writable)
+			parts[n].mask_flags = MTD_WRITEABLE;
+		n++;
+	}
+
+	ret = mtd_device_register(&spi->mtd, parts, n);
+
+	kfree(parts);
+
+	return ret;
+}
+
 static int i915_spi_probe(struct platform_device *platdev)
 {
 	struct resource *bar;
@@ -413,15 +484,28 @@ static int i915_spi_probe(struct platform_device *platdev)
 		return -ENODEV;
 	}
 
+	ret = i915_spi_init_mtd(spi, device, ret);
+	if (ret) {
+		dev_err(device, "i915-spi failed init mtd %d\n", ret);
+		return ret;
+	}
+
 	platform_set_drvdata(platdev, spi);
 
 	dev_dbg(device, "i915-spi is bound\n");
 
-	return 0;
+	return ret;
 }
 
 static int i915_spi_remove(struct platform_device *platdev)
 {
+	struct i915_spi *spi = platform_get_drvdata(platdev);
+
+	if (!spi)
+		return 0;
+
+	mtd_device_unregister(&spi->mtd);
+
 	platform_set_drvdata(platdev, NULL);
 
 	return 0;
-- 
2.26.2