s390/sclp: Add support for Store Data SCLP interface

Add functions to retrieve data associated with an SCLP Store Data
entity. Automatically retrieve data for the "config" entity during
boot and make that data available to user-space via sysfs:

    /sys/firmware/sclp_sd/config/data
        Reading from this file will return config data contents.

    /sys/firmware/sclp_sd/config/reload
        Writing to this file will cause the latest version of data
        related to the config entity to be read from the SCLP interface.

Generate a KOBJ_CHANGE whenever new data is retrieved.
Signed-off-by: NPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/Makefile

@@ -23,7 +23,7 @@ CFLAGS_REMOVE_sclp_early_core.o	+= $(CC_FLAGS_EXPOLINE)
 
 obj-y += ctrlchar.o keyboard.o defkeymap.o sclp.o sclp_rw.o sclp_quiesce.o \
 	 sclp_cmd.o sclp_config.o sclp_cpi_sys.o sclp_ocf.o sclp_ctl.o \
-	 sclp_early.o sclp_early_core.o
+	 sclp_early.o sclp_early_core.o sclp_sd.o
 
 obj-$(CONFIG_TN3270) += raw3270.o
 obj-$(CONFIG_TN3270_CONSOLE) += con3270.o

drivers/s390/char/sclp.h

@@ -28,6 +28,7 @@
 #define EVTYP_PMSGCMD		0x09
 #define EVTYP_ASYNC		0x0A
 #define EVTYP_CTLPROGIDENT	0x0B
+#define EVTYP_STORE_DATA	0x0C
 #define EVTYP_ERRNOTIFY		0x18
 #define EVTYP_VT220MSG		0x1A
 #define EVTYP_SDIAS		0x1C
@@ -42,6 +43,7 @@
 #define EVTYP_PMSGCMD_MASK	SCLP_EVTYP_MASK(EVTYP_PMSGCMD)
 #define EVTYP_ASYNC_MASK	SCLP_EVTYP_MASK(EVTYP_ASYNC)
 #define EVTYP_CTLPROGIDENT_MASK	SCLP_EVTYP_MASK(EVTYP_CTLPROGIDENT)
+#define EVTYP_STORE_DATA_MASK	SCLP_EVTYP_MASK(EVTYP_STORE_DATA)
 #define EVTYP_ERRNOTIFY_MASK	SCLP_EVTYP_MASK(EVTYP_ERRNOTIFY)
 #define EVTYP_VT220MSG_MASK	SCLP_EVTYP_MASK(EVTYP_VT220MSG)
 #define EVTYP_SDIAS_MASK	SCLP_EVTYP_MASK(EVTYP_SDIAS)

drivers/s390/char/sclp_sd.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SCLP Store Data support and sysfs interface
+ *
+ * Copyright IBM Corp. 2017
+ */
+
+#define KMSG_COMPONENT "sclp_sd"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/completion.h>
+#include <linux/kobject.h>
+#include <linux/list.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/async.h>
+#include <linux/export.h>
+#include <linux/mutex.h>
+
+#include <asm/pgalloc.h>
+
+#include "sclp.h"
+
+#define SD_EQ_STORE_DATA	0
+#define SD_EQ_HALT		1
+#define SD_EQ_SIZE		2
+
+#define SD_DI_CONFIG		3
+
+struct sclp_sd_evbuf {
+	struct evbuf_header hdr;
+	u8 eq;
+	u8 di;
+	u8 rflags;
+	u64 :56;
+	u32 id;
+	u16 :16;
+	u8 fmt;
+	u8 status;
+	u64 sat;
+	u64 sa;
+	u32 esize;
+	u32 dsize;
+} __packed;
+
+struct sclp_sd_sccb {
+	struct sccb_header hdr;
+	struct sclp_sd_evbuf evbuf;
+} __packed __aligned(PAGE_SIZE);
+
+/**
+ * struct sclp_sd_data - Result of a Store Data request
+ * @esize_bytes: Resulting esize in bytes
+ * @dsize_bytes: Resulting dsize in bytes
+ * @data: Pointer to data - must be released using vfree()
+ */
+struct sclp_sd_data {
+	size_t esize_bytes;
+	size_t dsize_bytes;
+	void *data;
+};
+
+/**
+ * struct sclp_sd_listener - Listener for asynchronous Store Data response
+ * @list: For enqueueing this struct
+ * @id: Event ID of response to listen for
+ * @completion: Can be used to wait for response
+ * @evbuf: Contains the resulting Store Data response after completion
+ */
+struct sclp_sd_listener {
+	struct list_head list;
+	u32 id;
+	struct completion completion;
+	struct sclp_sd_evbuf evbuf;
+};
+
+/**
+ * struct sclp_sd_file - Sysfs representation of a Store Data entity
+ * @kobj: Kobject
+ * @data_attr: Attribute for accessing data contents
+ * @data_mutex: Mutex to serialize access and updates to @data
+ * @data: Data associated with this entity
+ * @di: DI value associated with this entity
+ */
+struct sclp_sd_file {
+	struct kobject kobj;
+	struct bin_attribute data_attr;
+	struct mutex data_mutex;
+	struct sclp_sd_data data;
+	u8 di;
+};
+#define to_sd_file(x) container_of(x, struct sclp_sd_file, kobj)
+
+static struct kset *sclp_sd_kset;
+static struct sclp_sd_file *config_file;
+
+static LIST_HEAD(sclp_sd_queue);
+static DEFINE_SPINLOCK(sclp_sd_queue_lock);
+
+/**
+ * sclp_sd_listener_add() - Add listener for Store Data responses
+ * @listener: Listener to add
+ */
+static void sclp_sd_listener_add(struct sclp_sd_listener *listener)
+{
+	spin_lock_irq(&sclp_sd_queue_lock);
+	list_add_tail(&listener->list, &sclp_sd_queue);
+	spin_unlock_irq(&sclp_sd_queue_lock);
+}
+
+/**
+ * sclp_sd_listener_remove() - Remove listener for Store Data responses
+ * @listener: Listener to remove
+ */
+static void sclp_sd_listener_remove(struct sclp_sd_listener *listener)
+{
+	spin_lock_irq(&sclp_sd_queue_lock);
+	list_del(&listener->list);
+	spin_unlock_irq(&sclp_sd_queue_lock);
+}
+
+/**
+ * sclp_sd_listener_init() - Initialize a Store Data response listener
+ * @id: Event ID to listen for
+ *
+ * Initialize a listener for asynchronous Store Data responses. This listener
+ * can afterwards be used to wait for a specific response and to retrieve
+ * the associated response data.
+ */
+static void sclp_sd_listener_init(struct sclp_sd_listener *listener, u32 id)
+{
+	memset(listener, 0, sizeof(*listener));
+	listener->id = id;
+	init_completion(&listener->completion);
+}
+
+/**
+ * sclp_sd_receiver() - Receiver for Store Data events
+ * @evbuf_hdr: Header of received events
+ *
+ * Process Store Data events and complete listeners with matching event IDs.
+ */
+static void sclp_sd_receiver(struct evbuf_header *evbuf_hdr)
+{
+	struct sclp_sd_evbuf *evbuf = (struct sclp_sd_evbuf *) evbuf_hdr;
+	struct sclp_sd_listener *listener;
+	int found = 0;
+
+	pr_debug("received event (id=0x%08x)\n", evbuf->id);
+	spin_lock(&sclp_sd_queue_lock);
+	list_for_each_entry(listener, &sclp_sd_queue, list) {
+		if (listener->id != evbuf->id)
+			continue;
+
+		listener->evbuf = *evbuf;
+		complete(&listener->completion);
+		found = 1;
+		break;
+	}
+	spin_unlock(&sclp_sd_queue_lock);
+
+	if (!found)
+		pr_debug("unsolicited event (id=0x%08x)\n", evbuf->id);
+}
+
+static struct sclp_register sclp_sd_register = {
+	.send_mask = EVTYP_STORE_DATA_MASK,
+	.receive_mask = EVTYP_STORE_DATA_MASK,
+	.receiver_fn = sclp_sd_receiver,
+};
+
+/**
+ * sclp_sd_sync() - Perform Store Data request synchronously
+ * @page: Address of work page - must be below 2GB
+ * @eq: Input EQ value
+ * @di: Input DI value
+ * @sat: Input SAT value
+ * @sa: Input SA value used to specify the address of the target buffer
+ * @dsize_ptr: Optional pointer to input and output DSIZE value
+ * @esize_ptr: Optional pointer to output ESIZE value
+ *
+ * Perform Store Data request with specified parameters and wait for completion.
+ *
+ * Return %0 on success and store resulting DSIZE and ESIZE values in
+ * @dsize_ptr and @esize_ptr (if provided). Return non-zero on error.
+ */
+static int sclp_sd_sync(unsigned long page, u8 eq, u8 di, u64 sat, u64 sa,
+			u32 *dsize_ptr, u32 *esize_ptr)
+{
+	struct sclp_sd_sccb *sccb = (void *) page;
+	struct sclp_sd_listener listener;
+	struct sclp_sd_evbuf *evbuf;
+	int rc;
+
+	sclp_sd_listener_init(&listener, (u32) (addr_t) sccb);
+	sclp_sd_listener_add(&listener);
+
+	/* Prepare SCCB */
+	memset(sccb, 0, PAGE_SIZE);
+	sccb->hdr.length = sizeof(sccb->hdr) + sizeof(sccb->evbuf);
+	evbuf = &sccb->evbuf;
+	evbuf->hdr.length = sizeof(*evbuf);
+	evbuf->hdr.type = EVTYP_STORE_DATA;
+	evbuf->eq = eq;
+	evbuf->di = di;
+	evbuf->id = listener.id;
+	evbuf->fmt = 1;
+	evbuf->sat = sat;
+	evbuf->sa = sa;
+	if (dsize_ptr)
+		evbuf->dsize = *dsize_ptr;
+
+	/* Perform command */
+	pr_debug("request (eq=%d, di=%d, id=0x%08x)\n", eq, di, listener.id);
+	rc = sclp_sync_request(SCLP_CMDW_WRITE_EVENT_DATA, sccb);
+	pr_debug("request done (rc=%d)\n", rc);
+	if (rc)
+		goto out;
+
+	/* Evaluate response */
+	if (sccb->hdr.response_code == 0x73f0) {
+		pr_debug("event not supported\n");
+		rc = -EIO;
+		goto out_remove;
+	}
+	if (sccb->hdr.response_code != 0x0020 || !(evbuf->hdr.flags & 0x80)) {
+		rc = -EIO;
+		goto out;
+	}
+	if (!(evbuf->rflags & 0x80)) {
+		rc = wait_for_completion_interruptible(&listener.completion);
+		if (rc)
+			goto out;
+		evbuf = &listener.evbuf;
+	}
+	switch (evbuf->status) {
+	case 0:
+		if (dsize_ptr)
+			*dsize_ptr = evbuf->dsize;
+		if (esize_ptr)
+			*esize_ptr = evbuf->esize;
+		pr_debug("success (dsize=%u, esize=%u)\n", evbuf->dsize,
+			 evbuf->esize);
+		break;
+	case 3:
+		rc = -ENOENT;
+		break;
+	default:
+		rc = -EIO;
+		break;
+
+	}
+
+out:
+	if (rc && rc != -ENOENT) {
+		/* Provide some information about what went wrong */
+		pr_warn("Store Data request failed (eq=%d, di=%d, "
+			"response=0x%04x, flags=0x%02x, status=%d, rc=%d)\n",
+			eq, di, sccb->hdr.response_code, evbuf->hdr.flags,
+			evbuf->status, rc);
+	}
+
+out_remove:
+	sclp_sd_listener_remove(&listener);
+
+	return rc;
+}
+
+/**
+ * sclp_sd_store_data() - Obtain data for specified Store Data entity
+ * @result: Resulting data
+ * @di: DI value associated with this entity
+ *
+ * Perform a series of Store Data requests to obtain the size and contents of
+ * the specified Store Data entity.
+ *
+ * Return:
+ *   %0:       Success - result is stored in @result. @result->data must be
+ *	       released using vfree() after use.
+ *   %-ENOENT: No data available for this entity
+ *   %<0:      Other error
+ */
+static int sclp_sd_store_data(struct sclp_sd_data *result, u8 di)
+{
+	u32 dsize = 0, esize = 0;
+	unsigned long page, asce = 0;
+	void *data = NULL;
+	int rc;
+
+	page = __get_free_page(GFP_KERNEL | GFP_DMA);
+	if (!page)
+		return -ENOMEM;
+
+	/* Get size */
+	rc = sclp_sd_sync(page, SD_EQ_SIZE, di, 0, 0, &dsize, &esize);
+	if (rc)
+		goto out;
+	if (dsize == 0)
+		goto out_result;
+
+	/* Allocate memory */
+	data = vzalloc((size_t) dsize * PAGE_SIZE);
+	if (!data) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	/* Get translation table for buffer */
+	asce = base_asce_alloc((unsigned long) data, dsize);
+	if (!asce) {
+		vfree(data);
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	/* Get data */
+	rc = sclp_sd_sync(page, SD_EQ_STORE_DATA, di, asce, (u64) data, &dsize,
+			  &esize);
+	if (rc) {
+		/* Cancel running request if interrupted */
+		if (rc == -ERESTARTSYS)
+			sclp_sd_sync(page, SD_EQ_HALT, di, 0, 0, NULL, NULL);
+		vfree(data);
+		goto out;
+	}
+
+out_result:
+	result->esize_bytes = (size_t) esize * PAGE_SIZE;
+	result->dsize_bytes = (size_t) dsize * PAGE_SIZE;
+	result->data = data;
+
+out:
+	base_asce_free(asce);
+	free_page(page);
+
+	return rc;
+}
+
+/**
+ * sclp_sd_data_reset() - Reset Store Data result buffer
+ * @data: Data buffer to reset
+ *
+ * Reset @data to initial state and release associated memory.
+ */
+static void sclp_sd_data_reset(struct sclp_sd_data *data)
+{
+	vfree(data->data);
+	data->data = NULL;
+	data->dsize_bytes = 0;
+	data->esize_bytes = 0;
+}
+
+/**
+ * sclp_sd_file_release() - Release function for sclp_sd_file object
+ * @kobj: Kobject embedded in sclp_sd_file object
+ */
+static void sclp_sd_file_release(struct kobject *kobj)
+{
+	struct sclp_sd_file *sd_file = to_sd_file(kobj);
+
+	sclp_sd_data_reset(&sd_file->data);
+	kfree(sd_file);
+}
+
+/**
+ * sclp_sd_file_update() - Update contents of sclp_sd_file object
+ * @sd_file: Object to update
+ *
+ * Obtain the current version of data associated with the Store Data entity
+ * @sd_file.
+ *
+ * On success, return %0 and generate a KOBJ_CHANGE event to indicate that the
+ * data may have changed. Return non-zero otherwise.
+ */
+static int sclp_sd_file_update(struct sclp_sd_file *sd_file)
+{
+	const char *name = kobject_name(&sd_file->kobj);
+	struct sclp_sd_data data;
+	int rc;
+
+	rc = sclp_sd_store_data(&data, sd_file->di);
+	if (rc) {
+		if (rc == -ENOENT) {
+			pr_info("No data is available for the %s data entity\n",
+				 name);
+		}
+		return rc;
+	}
+
+	mutex_lock(&sd_file->data_mutex);
+	sclp_sd_data_reset(&sd_file->data);
+	sd_file->data = data;
+	mutex_unlock(&sd_file->data_mutex);
+
+	pr_info("A %zu-byte %s data entity was retrieved\n", data.dsize_bytes,
+		name);
+	kobject_uevent(&sd_file->kobj, KOBJ_CHANGE);
+
+	return 0;
+}
+
+/**
+ * sclp_sd_file_update_async() - Wrapper for asynchronous update call
+ * @data: Object to update
+ */
+static void sclp_sd_file_update_async(void *data, async_cookie_t cookie)
+{
+	struct sclp_sd_file *sd_file = data;
+
+	sclp_sd_file_update(sd_file);
+}
+
+/**
+ * reload_store() - Store function for "reload" sysfs attribute
+ * @kobj: Kobject of sclp_sd_file object
+ *
+ * Initiate a reload of the data associated with an sclp_sd_file object.
+ */
+static ssize_t reload_store(struct kobject *kobj, struct kobj_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct sclp_sd_file *sd_file = to_sd_file(kobj);
+
+	sclp_sd_file_update(sd_file);
+
+	return count;
+}
+
+static struct kobj_attribute reload_attr = __ATTR_WO(reload);
+
+static struct attribute *sclp_sd_file_default_attrs[] = {
+	&reload_attr.attr,
+	NULL,
+};
+
+static struct kobj_type sclp_sd_file_ktype = {
+	.sysfs_ops = &kobj_sysfs_ops,
+	.release = sclp_sd_file_release,
+	.default_attrs = sclp_sd_file_default_attrs,
+};
+
+/**
+ * data_read() - Read function for "read" sysfs attribute
+ * @kobj: Kobject of sclp_sd_file object
+ * @buffer: Target buffer
+ * @off: Requested file offset
+ * @size: Requested number of bytes
+ *
+ * Store the requested portion of the Store Data entity contents into the
+ * specified buffer. Return the number of bytes stored on success, or %0
+ * on EOF.
+ */
+static ssize_t data_read(struct file *file, struct kobject *kobj,
+			 struct bin_attribute *attr, char *buffer,
+			 loff_t off, size_t size)
+{
+	struct sclp_sd_file *sd_file = to_sd_file(kobj);
+	size_t data_size;
+	char *data;
+
+	mutex_lock(&sd_file->data_mutex);
+
+	data = sd_file->data.data;
+	data_size = sd_file->data.dsize_bytes;
+	if (!data || off >= data_size) {
+		size = 0;
+	} else {
+		if (off + size > data_size)
+			size = data_size - off;
+		memcpy(buffer, data + off, size);
+	}
+
+	mutex_unlock(&sd_file->data_mutex);
+
+	return size;
+}
+
+/**
+ * sclp_sd_file_create() - Add a sysfs file representing a Store Data entity
+ * @name: Name of file
+ * @di: DI value associated with this entity
+ *
+ * Create a sysfs directory with the given @name located under
+ *
+ *   /sys/firmware/sclp_sd/
+ *
+ * The files in this directory can be used to access the contents of the Store
+ * Data entity associated with @DI.
+ *
+ * Return pointer to resulting sclp_sd_file object on success, %NULL otherwise.
+ * The object must be freed by calling kobject_put() on the embedded kobject
+ * pointer after use.
+ */
+static __init struct sclp_sd_file *sclp_sd_file_create(const char *name, u8 di)
+{
+	struct sclp_sd_file *sd_file;
+	int rc;
+
+	sd_file = kzalloc(sizeof(*sd_file), GFP_KERNEL);
+	if (!sd_file)
+		return NULL;
+	sd_file->di = di;
+	mutex_init(&sd_file->data_mutex);
+
+	/* Create kobject located under /sys/firmware/sclp_sd/ */
+	sd_file->kobj.kset = sclp_sd_kset;
+	rc = kobject_init_and_add(&sd_file->kobj, &sclp_sd_file_ktype, NULL,
+				  "%s", name);
+	if (rc) {
+		kobject_put(&sd_file->kobj);
+		return NULL;
+	}
+
+	sysfs_bin_attr_init(&sd_file->data_attr);
+	sd_file->data_attr.attr.name = "data";
+	sd_file->data_attr.attr.mode = 0444;
+	sd_file->data_attr.read = data_read;
+
+	rc = sysfs_create_bin_file(&sd_file->kobj, &sd_file->data_attr);
+	if (rc) {
+		kobject_put(&sd_file->kobj);
+		return NULL;
+	}
+
+	/*
+	 * For completeness only - users interested in entity data should listen
+	 * for KOBJ_CHANGE instead.
+	 */
+	kobject_uevent(&sd_file->kobj, KOBJ_ADD);
+
+	/* Don't let a slow Store Data request delay further initialization */
+	async_schedule(sclp_sd_file_update_async, sd_file);
+
+	return sd_file;
+}
+
+/**
+ * sclp_sd_init() - Initialize sclp_sd support and register sysfs files
+ */
+static __init int sclp_sd_init(void)
+{
+	int rc;
+
+	rc = sclp_register(&sclp_sd_register);
+	if (rc)
+		return rc;
+
+	/* Create kset named "sclp_sd" located under /sys/firmware/ */
+	rc = -ENOMEM;
+	sclp_sd_kset = kset_create_and_add("sclp_sd", NULL, firmware_kobj);
+	if (!sclp_sd_kset)
+		goto err_kset;
+
+	rc = -EINVAL;
+	config_file = sclp_sd_file_create("config", SD_DI_CONFIG);
+	if (!config_file)
+		goto err_config;
+
+	return 0;
+
+err_config:
+	kset_unregister(sclp_sd_kset);
+err_kset:
+	sclp_unregister(&sclp_sd_register);
+
+	return rc;
+}
+device_initcall(sclp_sd_init);