[PATCH net-next v2 3/7] net: phy: introduce phy_read_mmd_poll_timeout macro

[Dejin Zheng <zhengdejin5@gmail.com>]

it is sometimes necessary to poll a phy register by phy_read_mmd()
function until its value satisfies some condition. introduce
phy_read_mmd_poll_timeout() macros that do this.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com>
---
v1 -> v2:
	- passed a phydev, device address and a reg to replace args...
	  parameter in phy_read_mmd_poll_timeout() by Andrew Lunn 's
	  suggestion. Andrew Lunn <andrew@lunn.ch>, Thanks very much for
	  your help!
	- handle phy_read_mmd return an error(the return value < 0) in
	  phy_read_mmd_poll_timeout(). Thanks Andrew again.

 include/linux/phy.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 36d9dea04016..bb351f8b8769 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -24,6 +24,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/u64_stats_sync.h>
 #include <linux/irqreturn.h>
+#include <linux/iopoll.h>
 
 #include <linux/atomic.h>
 
@@ -784,6 +785,19 @@ static inline int __phy_modify_changed(struct phy_device *phydev, u32 regnum,
  */
 int phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum);
 
+#define phy_read_mmd_poll_timeout(val, cond, sleep_us, timeout_us, \
+				  phydev, devad, regnum) \
+({ \
+	int ret = 0; \
+	ret = read_poll_timeout(phy_read_mmd, val, cond || val < 0, sleep_us, \
+				timeout_us, phydev, devad, regnum); \
+	if (val <  0) \
+		ret = val; \
+	if (ret) \
+		phydev_err(phydev, "%s failed: %d\n", __func__, ret); \
+	ret; \
+})
+
 /**
  * __phy_read_mmd - Convenience function for reading a register
  * from an MMD on a given PHY.
-- 
2.25.0