[RFC,ethtool-next,2/2] ethtool: Add ability to write to transceiver module EEPROM

diff --git a/ethtool.8.in b/ethtool.8.in
index 115322a21932..4c77c4bcaefa 100644
--- a/ethtool.8.in
+++ b/ethtool.8.in
@@ -369,6 +369,14 @@  ethtool \- query or control network driver and hardware settings
 .BN bank
 .BN i2c
 .HP
+.B ethtool \-M|\-\-change\-module\-eeprom
+.I devname
+.BN offset \ N
+.BN page \ N
+.BN bank \ N
+.BN i2c \ N
+.BN value \ N
+.HP
 .B ethtool \-\-show\-priv\-flags
 .I devname
 .HP
@@ -1188,6 +1196,27 @@  and
 .I length
 parameters are treated relatively to EEPROM page boundaries.
 .TP
+.B \-M \-\-change\-module\-eeprom
+Changes a single byte in the module EEPROM at the specified address to a
+specific value.
+.RS 4
+.TP
+.BI offset \ N
+Specifies the offset within a page to write to.
+.TP
+.BI page \ N
+Specifies the page number to write to.
+.TP
+.BI bank \ N
+Specifies the bank number to write to. If not specified, kernel assumes bank 0.
+.TP
+.BI i2c \ N
+Specifies the I2C address of the page to write to.
+.TP
+.BI value \ N
+Specifies the value to write.
+.RE
+.TP
 .B \-\-show\-priv\-flags
 Queries the specified network device for its private flags.  The
 names and meanings of private flags (if any) are defined by each
diff --git a/ethtool.c b/ethtool.c
index 33a0a492cb15..601bb409d0ae 100644
--- a/ethtool.c
+++ b/ethtool.c
@@ -5907,6 +5907,16 @@  static const struct option args[] = {
 			  "		[ bank N ]\n"
 			  "		[ i2c N ]\n"
 	},
+	{
+		.opts	= "-M|--change-module-eeprom",
+		.nlfunc = nl_setmodule,
+		.help	= "Change byte in device module EEPROM",
+		.xhelp	= "		[ offset N ]\n"
+			  "		[ page N ]\n"
+			  "		[ bank N ]\n"
+			  "		[ i2c N ]\n"
+			  "		[ value N ]\n"
+	},
 	{
 		.opts	= "--show-eee",
 		.func	= do_geee,
diff --git a/netlink/desc-ethtool.c b/netlink/desc-ethtool.c
index d6fc4e2d03df..4b86cd849f7d 100644
--- a/netlink/desc-ethtool.c
+++ b/netlink/desc-ethtool.c
@@ -408,6 +408,7 @@  const struct pretty_nlmsg_desc ethnl_umsg_desc[] = {
 	NLMSG_DESC(ETHTOOL_MSG_FEC_SET, fec),
 	NLMSG_DESC(ETHTOOL_MSG_STATS_GET, stats),
 	NLMSG_DESC(ETHTOOL_MSG_MODULE_EEPROM_GET, module_eeprom),
+	NLMSG_DESC(ETHTOOL_MSG_MODULE_EEPROM_SET, module_eeprom),
 };
 
 const unsigned int ethnl_umsg_n_desc = ARRAY_SIZE(ethnl_umsg_desc);
@@ -447,6 +448,7 @@  const struct pretty_nlmsg_desc ethnl_kmsg_desc[] = {
 	NLMSG_DESC(ETHTOOL_MSG_FEC_NTF, fec),
 	NLMSG_DESC(ETHTOOL_MSG_STATS_GET_REPLY, stats),
 	NLMSG_DESC(ETHTOOL_MSG_MODULE_EEPROM_GET_REPLY, module_eeprom),
+	NLMSG_DESC(ETHTOOL_MSG_MODULE_EEPROM_NTF, module_eeprom),
 };
 
 const unsigned int ethnl_kmsg_n_desc = ARRAY_SIZE(ethnl_kmsg_desc);
diff --git a/netlink/extapi.h b/netlink/extapi.h
index 91bf02b5e3be..0579c2abdb5d 100644
--- a/netlink/extapi.h
+++ b/netlink/extapi.h
@@ -45,6 +45,7 @@  bool nl_gstats_chk(struct cmd_context *ctx);
 int nl_gstats(struct cmd_context *ctx);
 int nl_monitor(struct cmd_context *ctx);
 int nl_getmodule(struct cmd_context *ctx);
+int nl_setmodule(struct cmd_context *ctx);
 
 void nl_monitor_usage(void);
 
@@ -99,6 +100,7 @@  static inline void nl_monitor_usage(void)
 #define nl_gstats_chk		NULL
 #define nl_gstats		NULL
 #define nl_getmodule		NULL
+#define nl_setmodule		NULL
 
 #endif /* ETHTOOL_ENABLE_NETLINK */
 
diff --git a/netlink/module-eeprom.c b/netlink/module-eeprom.c
index 355d1de047a8..5ce74e6b7731 100644
--- a/netlink/module-eeprom.c
+++ b/netlink/module-eeprom.c
@@ -1,7 +1,7 @@ 
 /*
- * module-eeprom.c - netlink implementation of module eeprom get command
+ * module-eeprom.c - netlink implementation of module eeprom commands
  *
- * ethtool -m <dev>
+ * Implementation of "ethtool -m <dev>" and "ethtool -M <dev> ..."
  */
 
 #include <errno.h>
@@ -18,6 +18,8 @@ 
 #include "netlink.h"
 #include "parser.h"
 
+/* MODULE_EEPROM_GET */
+
 #define ETH_I2C_ADDRESS_LOW	0x50
 #define ETH_I2C_ADDRESS_HIGH	0x51
 #define ETH_I2C_MAX_ADDRESS	0x7F
@@ -340,6 +342,43 @@  static void decoder_print(void)
 	}
 }
 
+int module_eeprom_ntf_cb(const struct nlmsghdr *nlhdr, void *data)
+{
+	const struct nlattr *tb[ETHTOOL_A_MODULE_EEPROM_MAX + 1] = {};
+	DECLARE_ATTR_TB_INFO(tb);
+	struct nl_context *nlctx = data;
+	bool silent;
+	int err_ret;
+	int ret;
+
+	silent = nlctx->is_dump || nlctx->is_monitor;
+	err_ret = silent ? MNL_CB_OK : MNL_CB_ERROR;
+	ret = mnl_attr_parse(nlhdr, GENL_HDRLEN, attr_cb, &tb_info);
+	if (ret < 0)
+		return err_ret;
+	if (!tb[ETHTOOL_A_MODULE_EEPROM_OFFSET] ||
+	    !tb[ETHTOOL_A_MODULE_EEPROM_LENGTH] ||
+	    !tb[ETHTOOL_A_MODULE_EEPROM_PAGE] ||
+	    !tb[ETHTOOL_A_MODULE_EEPROM_BANK] ||
+	    !tb[ETHTOOL_A_MODULE_EEPROM_I2C_ADDRESS])
+		return err_ret;
+	nlctx->devname = get_dev_name(tb[ETHTOOL_A_FEC_HEADER]);
+	if (!dev_ok(nlctx))
+		return err_ret;
+
+	if (silent)
+		putchar('\n');
+	printf("Module EEPROM write for %s:\n", nlctx->devname);
+	show_u32(tb[ETHTOOL_A_MODULE_EEPROM_OFFSET], "offset: ");
+	show_u32(tb[ETHTOOL_A_MODULE_EEPROM_LENGTH], "length: ");
+	printf("page: %u\n", mnl_attr_get_u8(tb[ETHTOOL_A_MODULE_EEPROM_PAGE]));
+	printf("bank: %u\n", mnl_attr_get_u8(tb[ETHTOOL_A_MODULE_EEPROM_BANK]));
+	printf("i2c address: 0x%x\n",
+	       mnl_attr_get_u8(tb[ETHTOOL_A_MODULE_EEPROM_I2C_ADDRESS]));
+
+	return MNL_CB_OK;
+}
+
 int nl_getmodule(struct cmd_context *ctx)
 {
 	struct ethtool_module_eeprom request = {0};
@@ -414,3 +453,85 @@  cleanup:
 	cache_free();
 	return ret;
 }
+
+/* MODULE_EEPROM_SET */
+
+static const struct param_parser setmodule_params[] = {
+	{
+		.arg		= "offset",
+		.type		= ETHTOOL_A_MODULE_EEPROM_OFFSET,
+		.handler	= nl_parse_direct_u32,
+		.min_argc	= 1,
+	},
+	{
+		.arg		= "page",
+		.type		= ETHTOOL_A_MODULE_EEPROM_PAGE,
+		.handler	= nl_parse_direct_u8,
+		.min_argc	= 1,
+	},
+	{
+		.arg		= "bank",
+		.type		= ETHTOOL_A_MODULE_EEPROM_BANK,
+		.handler	= nl_parse_direct_u8,
+		.min_argc	= 1,
+	},
+	{
+		.arg		= "i2c",
+		.type		= ETHTOOL_A_MODULE_EEPROM_I2C_ADDRESS,
+		.handler	= nl_parse_direct_u8,
+		.min_argc	= 1,
+	},
+	{
+		.arg		= "value",
+		.type		= ETHTOOL_A_MODULE_EEPROM_DATA,
+		.handler	= nl_parse_direct_u8,
+		.min_argc	= 1,
+	},
+	{}
+};
+
+int nl_setmodule(struct cmd_context *ctx)
+{
+	struct nl_context *nlctx = ctx->nlctx;
+	struct nl_msg_buff *msgbuff;
+	struct nl_socket *nlsk;
+	int ret;
+
+	if (netlink_cmd_check(ctx, ETHTOOL_MSG_MODULE_EEPROM_SET, false))
+		return -EOPNOTSUPP;
+	if (!ctx->argc) {
+		fprintf(stderr, "ethtool (-M): parameters missing\n");
+		return 1;
+	}
+
+	nlctx->cmd = "-M";
+	nlctx->argp = ctx->argp;
+	nlctx->argc = ctx->argc;
+	nlctx->devname = ctx->devname;
+	nlsk = nlctx->ethnl_socket;
+	msgbuff = &nlsk->msgbuff;
+
+	ret = msg_init(nlctx, msgbuff, ETHTOOL_MSG_MODULE_EEPROM_SET,
+		       NLM_F_REQUEST | NLM_F_ACK);
+	if (ret < 0)
+		return 2;
+	if (ethnla_fill_header(msgbuff, ETHTOOL_A_MODULE_EEPROM_HEADER,
+			       ctx->devname, 0))
+		return -EMSGSIZE;
+
+	ret = nl_parser(nlctx, setmodule_params, NULL, PARSER_GROUP_NONE, NULL);
+	if (ret < 0)
+		return 1;
+
+	if (ethnla_put_u32(msgbuff, ETHTOOL_A_MODULE_EEPROM_LENGTH, 1))
+		return -EMSGSIZE;
+
+	ret = nlsock_sendmsg(nlsk, NULL);
+	if (ret < 0)
+		return 83;
+	ret = nlsock_process_reply(nlsk, nomsg_reply_cb, nlctx);
+	if (ret == 0)
+		return 0;
+	else
+		return nlctx->exit_code ?: 83;
+}
diff --git a/netlink/monitor.c b/netlink/monitor.c
index 0c4df9e78ee3..ca4ebc7b0b9b 100644
--- a/netlink/monitor.c
+++ b/netlink/monitor.c
@@ -71,6 +71,10 @@  static struct {
 		.cmd	= ETHTOOL_MSG_FEC_NTF,
 		.cb	= fec_reply_cb,
 	},
+	{
+		.cmd	= ETHTOOL_MSG_MODULE_EEPROM_NTF,
+		.cb	= module_eeprom_ntf_cb,
+	},
 };
 
 static void clear_filter(struct nl_context *nlctx)
diff --git a/netlink/netlink.h b/netlink/netlink.h
index 70fa666b20e5..096a907c65c7 100644
--- a/netlink/netlink.h
+++ b/netlink/netlink.h
@@ -91,6 +91,7 @@  int cable_test_ntf_cb(const struct nlmsghdr *nlhdr, void *data);
 int cable_test_tdr_reply_cb(const struct nlmsghdr *nlhdr, void *data);
 int cable_test_tdr_ntf_cb(const struct nlmsghdr *nlhdr, void *data);
 int fec_reply_cb(const struct nlmsghdr *nlhdr, void *data);
+int module_eeprom_ntf_cb(const struct nlmsghdr *nlhdr, void *data);
 
 /* dump helpers */