From 2b93968fd1b9219ac88f82e6347b8728181759dc Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Wed, 2 Mar 2022 12:00:46 +0000
Subject: [PATCH] Add an interface to write to an nvmem cell.

ok patrick@
---
 sys/dev/ofw/ofw_misc.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 sys/dev/ofw/ofw_misc.h |  4 +++-
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/sys/dev/ofw/ofw_misc.c b/sys/dev/ofw/ofw_misc.c
index abb9f499cee..e0fbdf8b843 100644
--- a/sys/dev/ofw/ofw_misc.c
+++ b/sys/dev/ofw/ofw_misc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ofw_misc.c,v 1.34 2021/12/18 09:19:25 kettenis Exp $	*/
+/*	$OpenBSD: ofw_misc.c,v 1.35 2022/03/02 12:00:46 kettenis Exp $	*/
 /*
  * Copyright (c) 2017-2021 Mark Kettenis
  *
@@ -597,9 +597,48 @@ nvmem_read_cell(int node, const char *name, void *data, bus_size_t size)
 		return EINVAL;
 
 	nd = nc->nc_nd;
+	if (nd->nd_read == NULL)
+		return EACCES;
 	return nd->nd_read(nd->nd_cookie, nc->nc_addr, data, size);
 }
 
+int
+nvmem_write_cell(int node, const char *name, const void *data, bus_size_t size)
+{
+	struct nvmem_device *nd;
+	struct nvmem_cell *nc;
+	uint32_t phandle, *phandles;
+	int id, len;
+
+	id = OF_getindex(node, name, "nvmem-cell-names");
+	if (id < 0)
+		return ENXIO;
+
+	len = OF_getproplen(node, "nvmem-cells");
+	if (len <= 0)
+		return ENXIO;
+
+	phandles = malloc(len, M_TEMP, M_WAITOK);
+	OF_getpropintarray(node, "nvmem-cells", phandles, len);
+	phandle = phandles[id];
+	free(phandles, M_TEMP, len);
+
+	LIST_FOREACH(nc, &nvmem_cells, nc_list) {
+		if (nc->nc_phandle == phandle)
+			break;
+	}
+	if (nc == NULL)
+		return ENXIO;
+
+	if (size > nc->nc_size)
+		return EINVAL;
+
+	nd = nc->nc_nd;
+	if (nd->nd_write == NULL)
+		return EACCES;
+	return nd->nd_write(nd->nd_cookie, nc->nc_addr, data, size);
+}
+
 /* Port/endpoint interface support */
 
 LIST_HEAD(, endpoint) endpoints =
diff --git a/sys/dev/ofw/ofw_misc.h b/sys/dev/ofw/ofw_misc.h
index e294d306148..2dfa800a820 100644
--- a/sys/dev/ofw/ofw_misc.h
+++ b/sys/dev/ofw/ofw_misc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ofw_misc.h,v 1.22 2021/12/18 09:19:25 kettenis Exp $	*/
+/*	$OpenBSD: ofw_misc.h,v 1.23 2022/03/02 12:00:46 kettenis Exp $	*/
 /*
  * Copyright (c) 2017-2021 Mark Kettenis
  *
@@ -125,6 +125,7 @@ struct nvmem_device {
 	int	nd_node;
 	void	*nd_cookie;
 	int	(*nd_read)(void *, bus_addr_t, void *, bus_size_t);
+	int	(*nd_write)(void *, bus_addr_t, const void *, bus_size_t);
 
 	LIST_ENTRY(nvmem_device) nd_list;
 	uint32_t nd_phandle;
@@ -133,6 +134,7 @@ struct nvmem_device {
 void	nvmem_register(struct nvmem_device *);
 int	nvmem_read(uint32_t, bus_addr_t, void *, bus_size_t);
 int	nvmem_read_cell(int, const char *name, void *, bus_size_t);
+int	nvmem_write_cell(int, const char *name, const void *, bus_size_t);
 
 /* Port/endpoint interface support */
 
-- 
2.20.1