mtd: nand: ecc: Add infrastructure to support hardware engines

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>
Link: https://lore.kernel.org/linux-mtd/20211216111654.238086-13-miquel.raynal@bootlin.com

diff --git a/drivers/mtd/nand/core.c b/drivers/mtd/nand/core.c
index 416947f..ff34e3f 100644 (file)
--- a/drivers/mtd/nand/core.c
+++ b/drivers/mtd/nand/core.c
@@ -235,7 +235,9 @@ 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");
@@ -255,7 +257,7 @@ 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:
@@ -300,7 +302,9 @@ 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 6c43dfd..078f5ec 100644 (file)
--- 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 32fc7ed..4ddd20f 100644 (file)
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -264,11 +264,35 @@ struct nand_ecc_engine_ops {
 };
 
 /**
+ * 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);