ARM: OMAP: hwmod: wait for sysreset complete after enabling hwmod

When waking up from off-mode, some IP blocks are reset automatically by
hardware. For this reason, software must wait until the reset has
completed before attempting to access the IP block.

This patch fixes for example the bug introduced by commit
6c31b215 ("mmc: omap_hsmmc: remove access
to SYSCONFIG register"), in which the MMC IP block is reset during
off-mode entry, but the code expects the module to be already available
during the execution of context restore.

This version includes a fix from Kevin Hilman <khilman@ti.com> for
GPIO problems on the 37xx EVM - thanks Kevin.
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Venkatraman S <svenkatr@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
[paul@pwsan.com: moved softreset wait code into separate function; call
 from top of _enable_sysc() rather than the bottom; include fix from Kevin
 Hilman for GPIO sluggishness]
Signed-off-by: Paul Walmsley <paul@pwsan.com>

arch/arm/mach-omap2/omap_hwmod.c

@@ -421,6 +421,38 @@ static int _set_softreset(struct omap_hwmod *oh, u32 *v)
 	return 0;
 }
 
+/**
+ * _wait_softreset_complete - wait for an OCP softreset to complete
+ * @oh: struct omap_hwmod * to wait on
+ *
+ * Wait until the IP block represented by @oh reports that its OCP
+ * softreset is complete.  This can be triggered by software (see
+ * _ocp_softreset()) or by hardware upon returning from off-mode (one
+ * example is HSMMC).  Waits for up to MAX_MODULE_SOFTRESET_WAIT
+ * microseconds.  Returns the number of microseconds waited.
+ */
+static int _wait_softreset_complete(struct omap_hwmod *oh)
+{
+	struct omap_hwmod_class_sysconfig *sysc;
+	u32 softrst_mask;
+	int c = 0;
+
+	sysc = oh->class->sysc;
+
+	if (sysc->sysc_flags & SYSS_HAS_RESET_STATUS)
+		omap_test_timeout((omap_hwmod_read(oh, sysc->syss_offs)
+				   & SYSS_RESETDONE_MASK),
+				  MAX_MODULE_SOFTRESET_WAIT, c);
+	else if (sysc->sysc_flags & SYSC_HAS_RESET_STATUS) {
+		softrst_mask = (0x1 << sysc->sysc_fields->srst_shift);
+		omap_test_timeout(!(omap_hwmod_read(oh, sysc->sysc_offs)
+				    & softrst_mask),
+				  MAX_MODULE_SOFTRESET_WAIT, c);
+	}
+
+	return c;
+}
+
 /**
  * _set_dmadisable: set OCP_SYSCONFIG.DMADISABLE bit in @v
  * @oh: struct omap_hwmod *
@@ -1282,6 +1314,18 @@ static void _enable_sysc(struct omap_hwmod *oh)
 	if (!oh->class->sysc)
 		return;
 
+	/*
+	 * Wait until reset has completed, this is needed as the IP
+	 * block is reset automatically by hardware in some cases
+	 * (off-mode for example), and the drivers require the
+	 * IP to be ready when they access it
+	 */
+	if (oh->flags & HWMOD_CONTROL_OPT_CLKS_IN_RESET)
+		_enable_optional_clocks(oh);
+	_wait_softreset_complete(oh);
+	if (oh->flags & HWMOD_CONTROL_OPT_CLKS_IN_RESET)
+		_disable_optional_clocks(oh);
+
 	v = oh->_sysc_cache;
 	sf = oh->class->sysc->sysc_flags;
 
@@ -1804,7 +1848,7 @@ static int _am33xx_disable_module(struct omap_hwmod *oh)
  */
 static int _ocp_softreset(struct omap_hwmod *oh)
 {
-	u32 v, softrst_mask;
+	u32 v;
 	int c = 0;
 	int ret = 0;
 
@@ -1834,19 +1878,7 @@ static int _ocp_softreset(struct omap_hwmod *oh)
 	if (oh->class->sysc->srst_udelay)
 		udelay(oh->class->sysc->srst_udelay);
 
-	if (oh->class->sysc->sysc_flags & SYSS_HAS_RESET_STATUS)
-		omap_test_timeout((omap_hwmod_read(oh,
-						    oh->class->sysc->syss_offs)
-				   & SYSS_RESETDONE_MASK),
-				  MAX_MODULE_SOFTRESET_WAIT, c);
-	else if (oh->class->sysc->sysc_flags & SYSC_HAS_RESET_STATUS) {
-		softrst_mask = (0x1 << oh->class->sysc->sysc_fields->srst_shift);
-		omap_test_timeout(!(omap_hwmod_read(oh,
-						     oh->class->sysc->sysc_offs)
-				   & softrst_mask),
-				  MAX_MODULE_SOFTRESET_WAIT, c);
-	}
-
+	c = _wait_softreset_complete(oh);
 	if (c == MAX_MODULE_SOFTRESET_WAIT)
 		pr_warning("omap_hwmod: %s: softreset failed (waited %d usec)\n",
 			   oh->name, MAX_MODULE_SOFTRESET_WAIT);