1 files changed, 275 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/papr-vpd.c b/arch/powerpc/platforms/pseries/papr-vpd.c
new file mode 100644
index 000000000000..f38c188fc4a1
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/papr-vpd.c
@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt) "papr-vpd: " fmt
+
+#include <linux/build_bug.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/lockdep.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/string_helpers.h>
+#include <linux/uaccess.h>
+#include <asm/machdep.h>
+#include <asm/papr-vpd.h>
+#include <asm/rtas-work-area.h>
+#include <asm/rtas.h>
+#include <uapi/asm/papr-vpd.h>
+#include "papr-rtas-common.h"
+
+/**
+ * struct rtas_ibm_get_vpd_params - Parameters (in and out) for ibm,get-vpd.
+ * @loc_code:  In: Caller-provided location code buffer. Must be RTAS-addressable.
+ * @work_area: In: Caller-provided work area buffer for results.
+ * @sequence:  In: Sequence number. Out: Next sequence number.
+ * @written:   Out: Bytes written by ibm,get-vpd to @work_area.
+ * @status:    Out: RTAS call status.
+ */
+struct rtas_ibm_get_vpd_params {
+	const struct papr_location_code *loc_code;
+	struct rtas_work_area *work_area;
+	u32 sequence;
+	u32 written;
+	s32 status;
+};
+
+/**
+ * rtas_ibm_get_vpd() - Call ibm,get-vpd to fill a work area buffer.
+ * @params: See &struct rtas_ibm_get_vpd_params.
+ *
+ * Calls ibm,get-vpd until it errors or successfully deposits data
+ * into the supplied work area. Handles RTAS retry statuses. Maps RTAS
+ * error statuses to reasonable errno values.
+ *
+ * The caller is expected to invoke rtas_ibm_get_vpd() multiple times
+ * to retrieve all the VPD for the provided location code. Only one
+ * sequence should be in progress at any time; starting a new sequence
+ * will disrupt any sequence already in progress. Serialization of VPD
+ * retrieval sequences is the responsibility of the caller.
+ *
+ * The caller should inspect @params.status to determine whether more
+ * calls are needed to complete the sequence.
+ *
+ * Context: May sleep.
+ * Return: -ve on error, 0 otherwise.
+ */
+static int rtas_ibm_get_vpd(struct rtas_ibm_get_vpd_params *params)
+{
+	const struct papr_location_code *loc_code = params->loc_code;
+	struct rtas_work_area *work_area = params->work_area;
+	u32 rets[2];
+	s32 fwrc;
+	int ret;
+
+	lockdep_assert_held(&rtas_ibm_get_vpd_lock);
+
+	do {
+		fwrc = rtas_call(rtas_function_token(RTAS_FN_IBM_GET_VPD), 4, 3,
+				 rets,
+				 __pa(loc_code),
+				 rtas_work_area_phys(work_area),
+				 rtas_work_area_size(work_area),
+				 params->sequence);
+	} while (rtas_busy_delay(fwrc));
+
+	switch (fwrc) {
+	case RTAS_HARDWARE_ERROR:
+		ret = -EIO;
+		break;
+	case RTAS_INVALID_PARAMETER:
+		ret = -EINVAL;
+		break;
+	case RTAS_SEQ_START_OVER:
+		ret = -EAGAIN;
+		pr_info_ratelimited("VPD changed during retrieval, retrying\n");
+		break;
+	case RTAS_SEQ_MORE_DATA:
+		params->sequence = rets[0];
+		fallthrough;
+	case RTAS_SEQ_COMPLETE:
+		params->written = rets[1];
+		/*
+		 * Kernel or firmware bug, do not continue.
+		 */
+		if (WARN(params->written > rtas_work_area_size(work_area),
+			 "possible write beyond end of work area"))
+			ret = -EFAULT;
+		else
+			ret = 0;
+		break;
+	default:
+		ret = -EIO;
+		pr_err_ratelimited("unexpected ibm,get-vpd status %d\n", fwrc);
+		break;
+	}
+
+	params->status = fwrc;
+	return ret;
+}
+
+/*
+ * Internal VPD sequence APIs. A VPD sequence is a series of calls to
+ * ibm,get-vpd for a given location code. The sequence ends when an
+ * error is encountered or all VPD for the location code has been
+ * returned.
+ */
+
+/**
+ * vpd_sequence_begin() - Begin a VPD retrieval sequence.
+ * @seq: vpd call parameters from sequence struct
+ *
+ * Context: May sleep.
+ */
+static void vpd_sequence_begin(struct papr_rtas_sequence *seq)
+{
+	struct rtas_ibm_get_vpd_params *vpd_params;
+	/*
+	 * Use a static data structure for the location code passed to
+	 * RTAS to ensure it's in the RMA and avoid a separate work
+	 * area allocation. Guarded by the function lock.
+	 */
+	static struct papr_location_code static_loc_code;
+
+	vpd_params =  (struct rtas_ibm_get_vpd_params *)seq->params;
+	/*
+	 * We could allocate the work area before acquiring the
+	 * function lock, but that would allow concurrent requests to
+	 * exhaust the limited work area pool for no benefit. So
+	 * allocate the work area under the lock.
+	 */
+	mutex_lock(&rtas_ibm_get_vpd_lock);
+	static_loc_code = *(struct papr_location_code *)vpd_params->loc_code;
+	vpd_params =  (struct rtas_ibm_get_vpd_params *)seq->params;
+	vpd_params->work_area = rtas_work_area_alloc(SZ_4K);
+	vpd_params->loc_code = &static_loc_code;
+	vpd_params->sequence = 1;
+	vpd_params->status = 0;
+}
+
+/**
+ * vpd_sequence_end() - Finalize a VPD retrieval sequence.
+ * @seq: Sequence state.
+ *
+ * Releases resources obtained by vpd_sequence_begin().
+ */
+static void vpd_sequence_end(struct papr_rtas_sequence *seq)
+{
+	struct rtas_ibm_get_vpd_params *vpd_params;
+
+	vpd_params =  (struct rtas_ibm_get_vpd_params *)seq->params;
+	rtas_work_area_free(vpd_params->work_area);
+	mutex_unlock(&rtas_ibm_get_vpd_lock);
+}
+
+/*
+ * Generator function to be passed to papr_rtas_blob_generate().
+ */
+static const char *vpd_sequence_fill_work_area(struct papr_rtas_sequence *seq,
+						size_t *len)
+{
+	struct rtas_ibm_get_vpd_params *p;
+	bool init_state;
+
+	p = (struct rtas_ibm_get_vpd_params *)seq->params;
+	init_state = (p->written == 0) ? true : false;
+
+	if (papr_rtas_sequence_should_stop(seq, p->status, init_state))
+		return NULL;
+	if (papr_rtas_sequence_set_err(seq, rtas_ibm_get_vpd(p)))
+		return NULL;
+	*len = p->written;
+	return rtas_work_area_raw_buf(p->work_area);
+}
+
+static const struct file_operations papr_vpd_handle_ops = {
+	.read = papr_rtas_common_handle_read,
+	.llseek = papr_rtas_common_handle_seek,
+	.release = papr_rtas_common_handle_release,
+};
+
+/**
+ * papr_vpd_create_handle() - Create a fd-based handle for reading VPD.
+ * @ulc: Location code in user memory; defines the scope of the VPD to
+ *       retrieve.
+ *
+ * Handler for PAPR_VPD_IOC_CREATE_HANDLE ioctl command. Validates
+ * @ulc and instantiates an immutable VPD "blob" for it. The blob is
+ * attached to a file descriptor for reading by user space. The memory
+ * backing the blob is freed when the file is released.
+ *
+ * The entire requested VPD is retrieved by this call and all
+ * necessary RTAS interactions are performed before returning the fd
+ * to user space. This keeps the read handler simple and ensures that
+ * the kernel can prevent interleaving of ibm,get-vpd call sequences.
+ *
+ * Return: The installed fd number if successful, -ve errno otherwise.
+ */
+static long papr_vpd_create_handle(struct papr_location_code __user *ulc)
+{
+	struct rtas_ibm_get_vpd_params vpd_params = {};
+	struct papr_rtas_sequence seq = {};
+	struct papr_location_code klc;
+	int fd;
+
+	if (copy_from_user(&klc, ulc, sizeof(klc)))
+		return -EFAULT;
+
+	if (!string_is_terminated(klc.str, ARRAY_SIZE(klc.str)))
+		return -EINVAL;
+
+	seq = (struct papr_rtas_sequence) {
+		.begin = vpd_sequence_begin,
+		.end = vpd_sequence_end,
+		.work = vpd_sequence_fill_work_area,
+	};
+
+	vpd_params.loc_code = &klc;
+	seq.params = (void *)&vpd_params;
+
+	fd = papr_rtas_setup_file_interface(&seq, &papr_vpd_handle_ops,
+			"[papr-vpd]");
+
+	return fd;
+}
+
+/*
+ * Top-level ioctl handler for /dev/papr-vpd.
+ */
+static long papr_vpd_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+	void __user *argp = (__force void __user *)arg;
+	long ret;
+
+	switch (ioctl) {
+	case PAPR_VPD_IOC_CREATE_HANDLE:
+		ret = papr_vpd_create_handle(argp);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+	return ret;
+}
+
+static const struct file_operations papr_vpd_ops = {
+	.unlocked_ioctl = papr_vpd_dev_ioctl,
+};
+
+static struct miscdevice papr_vpd_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "papr-vpd",
+	.fops = &papr_vpd_ops,
+};
+
+static __init int papr_vpd_init(void)
+{
+	if (!rtas_function_implemented(RTAS_FN_IBM_GET_VPD))
+		return -ENODEV;
+
+	return misc_register(&papr_vpd_dev);
+}
+machine_device_initcall(pseries, papr_vpd_init);