1 files changed, 292 insertions, 0 deletions
diff --git a/drivers/mtd/devices/powernv_flash.c b/drivers/mtd/devices/powernv_flash.c
new file mode 100644
index 000000000..0b757d9ba
--- /dev/null
+++ b/drivers/mtd/devices/powernv_flash.c
@@ -0,0 +1,292 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * OPAL PNOR flash MTD abstraction
+ *
+ * Copyright IBM 2015
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+#include <asm/opal.h>
+
+
+/*
+ * This driver creates the a Linux MTD abstraction for platform PNOR flash
+ * backed by OPAL calls
+ */
+
+struct powernv_flash {
+	struct mtd_info	mtd;
+	u32 id;
+};
+
+enum flash_op {
+	FLASH_OP_READ,
+	FLASH_OP_WRITE,
+	FLASH_OP_ERASE,
+};
+
+/*
+ * Don't return -ERESTARTSYS if we can't get a token, the MTD core
+ * might have split up the call from userspace and called into the
+ * driver more than once, we'll already have done some amount of work.
+ */
+static int powernv_flash_async_op(struct mtd_info *mtd, enum flash_op op,
+		loff_t offset, size_t len, size_t *retlen, u_char *buf)
+{
+	struct powernv_flash *info = (struct powernv_flash *)mtd->priv;
+	struct device *dev = &mtd->dev;
+	int token;
+	struct opal_msg msg;
+	int rc;
+
+	dev_dbg(dev, "%s(op=%d, offset=0x%llx, len=%zu)\n",
+			__func__, op, offset, len);
+
+	token = opal_async_get_token_interruptible();
+	if (token < 0) {
+		if (token != -ERESTARTSYS)
+			dev_err(dev, "Failed to get an async token\n");
+		else
+			token = -EINTR;
+		return token;
+	}
+
+	switch (op) {
+	case FLASH_OP_READ:
+		rc = opal_flash_read(info->id, offset, __pa(buf), len, token);
+		break;
+	case FLASH_OP_WRITE:
+		rc = opal_flash_write(info->id, offset, __pa(buf), len, token);
+		break;
+	case FLASH_OP_ERASE:
+		rc = opal_flash_erase(info->id, offset, len, token);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		opal_async_release_token(token);
+		return -EIO;
+	}
+
+	if (rc == OPAL_ASYNC_COMPLETION) {
+		rc = opal_async_wait_response_interruptible(token, &msg);
+		if (rc) {
+			/*
+			 * If we return the mtd core will free the
+			 * buffer we've just passed to OPAL but OPAL
+			 * will continue to read or write from that
+			 * memory.
+			 * It may be tempting to ultimately return 0
+			 * if we're doing a read or a write since we
+			 * are going to end up waiting until OPAL is
+			 * done. However, because the MTD core sends
+			 * us the userspace request in chunks, we need
+			 * it to know we've been interrupted.
+			 */
+			rc = -EINTR;
+			if (opal_async_wait_response(token, &msg))
+				dev_err(dev, "opal_async_wait_response() failed\n");
+			goto out;
+		}
+		rc = opal_get_async_rc(msg);
+	}
+
+	/*
+	 * OPAL does mutual exclusion on the flash, it will return
+	 * OPAL_BUSY.
+	 * During firmware updates by the service processor OPAL may
+	 * be (temporarily) prevented from accessing the flash, in
+	 * this case OPAL will also return OPAL_BUSY.
+	 * Both cases aren't errors exactly but the flash could have
+	 * changed, userspace should be informed.
+	 */
+	if (rc != OPAL_SUCCESS && rc != OPAL_BUSY)
+		dev_err(dev, "opal_flash_async_op(op=%d) failed (rc %d)\n",
+				op, rc);
+
+	if (rc == OPAL_SUCCESS && retlen)
+		*retlen = len;
+
+	rc = opal_error_code(rc);
+out:
+	opal_async_release_token(token);
+	return rc;
+}
+
+/**
+ * @mtd: the device
+ * @from: the offset to read from
+ * @len: the number of bytes to read
+ * @retlen: the number of bytes actually read
+ * @buf: the filled in buffer
+ *
+ * Returns 0 if read successful, or -ERRNO if an error occurred
+ */
+static int powernv_flash_read(struct mtd_info *mtd, loff_t from, size_t len,
+	     size_t *retlen, u_char *buf)
+{
+	return powernv_flash_async_op(mtd, FLASH_OP_READ, from,
+			len, retlen, buf);
+}
+
+/**
+ * @mtd: the device
+ * @to: the offset to write to
+ * @len: the number of bytes to write
+ * @retlen: the number of bytes actually written
+ * @buf: the buffer to get bytes from
+ *
+ * Returns 0 if write successful, -ERRNO if error occurred
+ */
+static int powernv_flash_write(struct mtd_info *mtd, loff_t to, size_t len,
+		     size_t *retlen, const u_char *buf)
+{
+	return powernv_flash_async_op(mtd, FLASH_OP_WRITE, to,
+			len, retlen, (u_char *)buf);
+}
+
+/**
+ * @mtd: the device
+ * @erase: the erase info
+ * Returns 0 if erase successful or -ERRNO if an error occurred
+ */
+static int powernv_flash_erase(struct mtd_info *mtd, struct erase_info *erase)
+{
+	int rc;
+
+	rc =  powernv_flash_async_op(mtd, FLASH_OP_ERASE, erase->addr,
+			erase->len, NULL, NULL);
+	if (rc)
+		erase->fail_addr = erase->addr;
+
+	return rc;
+}
+
+/**
+ * powernv_flash_set_driver_info - Fill the mtd_info structure and docg3
+ * structure @pdev: The platform device
+ * @mtd: The structure to fill
+ */
+static int powernv_flash_set_driver_info(struct device *dev,
+		struct mtd_info *mtd)
+{
+	u64 size;
+	u32 erase_size;
+	int rc;
+
+	rc = of_property_read_u32(dev->of_node, "ibm,flash-block-size",
+			&erase_size);
+	if (rc) {
+		dev_err(dev, "couldn't get resource block size information\n");
+		return rc;
+	}
+
+	rc = of_property_read_u64(dev->of_node, "reg", &size);
+	if (rc) {
+		dev_err(dev, "couldn't get resource size information\n");
+		return rc;
+	}
+
+	/*
+	 * Going to have to check what details I need to set and how to
+	 * get them
+	 */
+	mtd->name = devm_kasprintf(dev, GFP_KERNEL, "%pOFP", dev->of_node);
+	mtd->type = MTD_NORFLASH;
+	mtd->flags = MTD_WRITEABLE;
+	mtd->size = size;
+	mtd->erasesize = erase_size;
+	mtd->writebufsize = mtd->writesize = 1;
+	mtd->owner = THIS_MODULE;
+	mtd->_erase = powernv_flash_erase;
+	mtd->_read = powernv_flash_read;
+	mtd->_write = powernv_flash_write;
+	mtd->dev.parent = dev;
+	mtd_set_of_node(mtd, dev->of_node);
+	return 0;
+}
+
+/**
+ * powernv_flash_probe
+ * @pdev: platform device
+ *
+ * Returns 0 on success, -ENOMEM, -ENXIO on error
+ */
+static int powernv_flash_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct powernv_flash *data;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->mtd.priv = data;
+
+	ret = of_property_read_u32(dev->of_node, "ibm,opal-id", &(data->id));
+	if (ret) {
+		dev_err(dev, "no device property 'ibm,opal-id'\n");
+		return ret;
+	}
+
+	ret = powernv_flash_set_driver_info(dev, &data->mtd);
+	if (ret)
+		return ret;
+
+	dev_set_drvdata(dev, data);
+
+	/*
+	 * The current flash that skiboot exposes is one contiguous flash chip
+	 * with an ffs partition at the start, it should prove easier for users
+	 * to deal with partitions or not as they see fit
+	 */
+	return mtd_device_register(&data->mtd, NULL, 0);
+}
+
+/**
+ * op_release - Release the driver
+ * @pdev: the platform device
+ *
+ * Returns 0
+ */
+static int powernv_flash_release(struct platform_device *pdev)
+{
+	struct powernv_flash *data = dev_get_drvdata(&(pdev->dev));
+
+	/* All resources should be freed automatically */
+	return mtd_device_unregister(&(data->mtd));
+}
+
+static const struct of_device_id powernv_flash_match[] = {
+	{ .compatible = "ibm,opal-flash" },
+	{}
+};
+
+static struct platform_driver powernv_flash_driver = {
+	.driver		= {
+		.name		= "powernv_flash",
+		.of_match_table	= powernv_flash_match,
+	},
+	.remove		= powernv_flash_release,
+	.probe		= powernv_flash_probe,
+};
+
+module_platform_driver(powernv_flash_driver);
+
+MODULE_DEVICE_TABLE(of, powernv_flash_match);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Cyril Bur <cyril.bur@au1.ibm.com>");
+MODULE_DESCRIPTION("MTD abstraction for OPAL flash");