ixp4xx_eth: make ptp support a platform driver

After the recent ixp4xx cleanups, the ptp driver has gained a
build failure in some configurations:

drivers/net/ethernet/xscale/ptp_ixp46x.c: In function 'ptp_ixp_init':
drivers/net/ethernet/xscale/ptp_ixp46x.c:290:51: error: 'IXP4XX_TIMESYNC_BASE_VIRT' undeclared (first use in this function)

Avoid the last bit of hardcoded constants from platform headers
by turning the ptp driver bit into a platform driver and passing
the IRQ and MMIO address as resources.

This is a bit tricky:

- The interface between the two drivers is now the new
  ixp46x_ptp_find() function, replacing the global
  ixp46x_phc_index variable. The call is done as late
  as possible, in hwtstamp_set(), to ensure that the
  ptp device is fully probed.

- As the ptp driver is now called by the network driver, the
  link dependency is reversed, which in turn requires a small
  Makefile hack

- The GPIO number is still left hardcoded. This is clearly not
  great, but it can be addressed later. Note that commit 98ac0cc270b7
  ("ARM: ixp4xx: Convert to MULTI_IRQ_HANDLER") changed the
  IRQ number to something meaningless. Passing the correct IRQ
  in a resource fixes this.

- When the PTP driver is disabled, ethtool .get_ts_info()
  now correctly lists only software timestamping regardless
  of the hardware.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[Fix a missing include]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/net/ethernet/xscale/ixp46x_ts.h b/drivers/net/ethernet/xscale/ixp46x_ts.h
index d792130e27b0..ee9b93ded20a 100644
--- a/drivers/net/ethernet/xscale/ixp46x_ts.h
+++ b/drivers/net/ethernet/xscale/ixp46x_ts.h
@@ -62,7 +62,16 @@ struct ixp46x_ts_regs {
 #define TX_SNAPSHOT_LOCKED (1<<0)
 #define RX_SNAPSHOT_LOCKED (1<<1)
 
-/* The ptp_ixp46x module will set this variable */
-extern int ixp46x_phc_index;
+#if IS_ENABLED(CONFIG_PTP_1588_CLOCK_IXP46X)
+int ixp46x_ptp_find(struct ixp46x_ts_regs *__iomem *regs, int *phc_index);
+#else
+static inline int ixp46x_ptp_find(struct ixp46x_ts_regs *__iomem *regs, int *phc_index)
+{
+	*regs = NULL;
+	*phc_index = -1;
+
+	return -ENODEV;
+}
+#endif
 
 #endif