[PATCH v3 12/22] mtd: nand: ecc: Add infrastructure to support hardware engines

Miquel Raynal
2021-12-07T09:48:42Z

Add the necessary helpers to register/unregister hardware ECC engines
that will be called from ECC engine drivers.

Also add helpers to get the right engine from the user
perspective. Keep a reference of the in use ECC engine in order to
prevent modules to be unloaded. Put the reference when the engine gets
retired.

A static list of hardware (only) ECC engines is setup to keep track of
the registered engines.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
drivers/mtd/nand/core.c | 10 +++--
drivers/mtd/nand/ecc.c | 88 ++++++++++++++++++++++++++++++++++++++++
include/linux/mtd/nand.h | 28 +++++++++++++
3 files changed, 123 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/core.c b/drivers/mtd/nand/core.c
index df9646685c91..5628bd410f7e 100644
--- a/drivers/mtd/nand/core.c
+++ b/drivers/mtd/nand/core.c
@@ -232,7 +232,9 @@ static int nanddev_get_ecc_engine(struct nand_device *nand)
nand->ecc.engine = nand_ecc_get_on_die_hw_engine(nand);
break;
case NAND_ECC_ENGINE_TYPE_ON_HOST:
- pr_err("On-host hardware ECC engines not supported yet\n");
+ nand->ecc.engine = nand_ecc_get_on_host_hw_engine(nand);
+ if (PTR_ERR(nand->ecc.engine) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
break;
default:
pr_err("Missing ECC engine type\n");
@@ -252,7 +254,7 @@ static int nanddev_put_ecc_engine(struct nand_device *nand)
{
switch (nand->ecc.ctx.conf.engine_type) {
case NAND_ECC_ENGINE_TYPE_ON_HOST:
- pr_err("On-host hardware ECC engines not supported yet\n");
+ nand_ecc_put_on_host_hw_engine(nand);
break;
case NAND_ECC_ENGINE_TYPE_NONE:
case NAND_ECC_ENGINE_TYPE_SOFT:
@@ -297,7 +299,9 @@ int nanddev_ecc_engine_init(struct nand_device *nand)
/* Look for the ECC engine to use */
ret = nanddev_get_ecc_engine(nand);
if (ret) {
- pr_err("No ECC engine found\n");
+ if (ret != -EPROBE_DEFER)
+ pr_err("No ECC engine found\n");
+
return ret;
}

diff --git a/drivers/mtd/nand/ecc.c b/drivers/mtd/nand/ecc.c
index 6c43dfda01d4..078f5ec38de3 100644
--- a/drivers/mtd/nand/ecc.c
+++ b/drivers/mtd/nand/ecc.c
@@ -96,6 +96,12 @@
#include <linux/module.h>
#include <linux/mtd/nand.h>
#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+
+static LIST_HEAD(on_host_hw_engines);
+static DEFINE_MUTEX(on_host_hw_engines_mutex);

/**
* nand_ecc_init_ctx - Init the ECC engine context
@@ -611,6 +617,88 @@ struct nand_ecc_engine *nand_ecc_get_on_die_hw_engine(struct nand_device *nand)
}
EXPORT_SYMBOL(nand_ecc_get_on_die_hw_engine);

+int nand_ecc_register_on_host_hw_engine(struct nand_ecc_engine *engine)
+{
+ struct nand_ecc_engine *item;
+
+ if (!engine)
+ return -EINVAL;
+
+ /* Prevent multiple registrations of one engine */
+ list_for_each_entry(item, &on_host_hw_engines, node)
+ if (item == engine)
+ return 0;
+
+ mutex_lock(&on_host_hw_engines_mutex);
+ list_add_tail(&engine->node, &on_host_hw_engines);
+ mutex_unlock(&on_host_hw_engines_mutex);
+
+ return 0;
+}
+EXPORT_SYMBOL(nand_ecc_register_on_host_hw_engine);
+
+int nand_ecc_unregister_on_host_hw_engine(struct nand_ecc_engine *engine)
+{
+ if (!engine)
+ return -EINVAL;
+
+ mutex_lock(&on_host_hw_engines_mutex);
+ list_del(&engine->node);
+ mutex_unlock(&on_host_hw_engines_mutex);
+
+ return 0;
+}
+EXPORT_SYMBOL(nand_ecc_unregister_on_host_hw_engine);
+
+static struct nand_ecc_engine *nand_ecc_match_on_host_hw_engine(struct device *dev)
+{
+ struct nand_ecc_engine *item;
+
+ list_for_each_entry(item, &on_host_hw_engines, node)
+ if (item->dev == dev)
+ return item;
+
+ return NULL;
+}
+
+struct nand_ecc_engine *nand_ecc_get_on_host_hw_engine(struct nand_device *nand)
+{
+ struct nand_ecc_engine *engine = NULL;
+ struct device *dev = &nand->mtd.dev;
+ struct platform_device *pdev;
+ struct device_node *np;
+
+ if (list_empty(&on_host_hw_engines))
+ return NULL;
+
+ /* Check for an explicit nand-ecc-engine property */
+ np = of_parse_phandle(dev->of_node, "nand-ecc-engine", 0);
+ if (np) {
+ pdev = of_find_device_by_node(np);
+ if (!pdev)
+ return ERR_PTR(-EPROBE_DEFER);
+
+ engine = nand_ecc_match_on_host_hw_engine(&pdev->dev);
+ platform_device_put(pdev);
+ of_node_put(np);
+
+ if (!engine)
+ return ERR_PTR(-EPROBE_DEFER);
+ }
+
+ if (engine)
+ get_device(engine->dev);
+
+ return engine;
+}
+EXPORT_SYMBOL(nand_ecc_get_on_host_hw_engine);
+
+void nand_ecc_put_on_host_hw_engine(struct nand_device *nand)
+{
+ put_device(nand->ecc.engine->dev);
+}
+EXPORT_SYMBOL(nand_ecc_put_on_host_hw_engine);
+
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Miquel Raynal <miquel.raynal@bootlin.com>");
MODULE_DESCRIPTION("Generic ECC engine");
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 32fc7edf65b3..4ddd20fe9c9e 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -263,12 +263,36 @@ struct nand_ecc_engine_ops {
struct nand_page_io_req *req);
};

+/**
+ * enum nand_ecc_engine_integration - How the NAND ECC engine is integrated
+ * @NAND_ECC_ENGINE_INTEGRATION_INVALID: Invalid value
+ * @NAND_ECC_ENGINE_INTEGRATION_PIPELINED: Pipelined engine, performs on-the-fly
+ * correction, does not need to copy
+ * data around
+ * @NAND_ECC_ENGINE_INTEGRATION_EXTERNAL: External engine, needs to bring the
+ * data into its own area before use
+ */
+enum nand_ecc_engine_integration {
+ NAND_ECC_ENGINE_INTEGRATION_INVALID,
+ NAND_ECC_ENGINE_INTEGRATION_PIPELINED,
+ NAND_ECC_ENGINE_INTEGRATION_EXTERNAL,
+};
+
/**
* struct nand_ecc_engine - ECC engine abstraction for NAND devices
+ * @dev: Host device
+ * @node: Private field for registration time
* @ops: ECC engine operations
+ * @integration: How the engine is integrated with the host
+ * (only relevant on %NAND_ECC_ENGINE_TYPE_ON_HOST engines)
+ * @priv: Private data
*/
struct nand_ecc_engine {
+ struct device *dev;
+ struct list_head node;
struct nand_ecc_engine_ops *ops;
+ enum nand_ecc_engine_integration integration;
+ void *priv;
};

void of_get_nand_ecc_user_config(struct nand_device *nand);
@@ -279,8 +303,12 @@ int nand_ecc_prepare_io_req(struct nand_device *nand,
int nand_ecc_finish_io_req(struct nand_device *nand,
struct nand_page_io_req *req);
bool nand_ecc_is_strong_enough(struct nand_device *nand);
+int nand_ecc_register_on_host_hw_engine(struct nand_ecc_engine *engine);
+int nand_ecc_unregister_on_host_hw_engine(struct nand_ecc_engine *engine);
struct nand_ecc_engine *nand_ecc_get_sw_engine(struct nand_device *nand);
struct nand_ecc_engine *nand_ecc_get_on_die_hw_engine(struct nand_device *nand);
+struct nand_ecc_engine *nand_ecc_get_on_host_hw_engine(struct nand_device *nand);
+void nand_ecc_put_on_host_hw_engine(struct nand_device *nand);

#if IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING)
struct nand_ecc_engine *nand_ecc_sw_hamming_get_engine(void);