ARM: OMAP2+: hwmod: revise hardreset behavior

Change the way that hardreset lines are handled by the hwmod code.
Hardreset lines are generally associated with initiator IP blocks.
Prior to this change, the hwmod code expected to control hardreset
lines itself, asserting them on shutdown and deasserting them upon
enable.  But driver authors inside TI have commented to us that their
drivers require direct control over these lines.  Unfortunately, these
drivers haven't been posted publicly yet, so it's hard to determine
exactly what is needed, a priori.  This change attempts to set forth
some reasonable semantics that should be an improvement over the
current code.

The semantics implemented by this patch are as follows:

- If the hwmod is not marked with HWMOD_INIT_NO_RESET, then assert all
  associated hardreset lines during IP block setup.  This is intended
  to place the IP blocks into a known state that will not interfere
  with other devices during kernel boot.

- IP blocks with hardreset lines will not be automatically enabled or
  idled during setup.  Instead, they will be left in the INITIALIZED
  state.

- When the hwmod code is asked to enable, idle, or shutdown an IP
  block with asserted hardreset lines, the hwmod code will do nothing.
  The driver integration code must do the remaining work needed to
  control these IP blocks.  Once this driver integration code is posted
  to the lists, hopefully we can consolidate it and move it inside the
  hwmod code.

Custom reset functions for IP blocks with hardreset lines still should
be supported and are strongly endorsed.  It is intended that every
subsystem with hardreset lines should have a custom reset function
that can place their subsystem into quiescent idle with the hardreset
lines deasserted.

This reverts most of commit 5365efbe29250a227502256cc912351fe2157b42
("OMAP: hwmod: Add hardreset management support").  Later code
reorganizations caused the sequencing of the code from this patch to
be changed, anyway.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Benoît Cousson <b-cousson@ti.com>

1 files changed, 83 insertions, 56 deletions

diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 6c6d31b432d2..bd9fc10ea737 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -781,39 +781,6 @@ static int _omap4_wait_target_disable(struct omap_hwmod *oh)
 }
 
 /**
- * _omap4_disable_module - enable CLKCTRL modulemode on OMAP4
- * @oh: struct omap_hwmod *
- *
- * Disable the PRCM module mode related to the hwmod @oh.
- * Return EINVAL if the modulemode is not supported and 0 in case of success.
- */
-static int _omap4_disable_module(struct omap_hwmod *oh)
-{
-        int v;
-
-        /* The module mode does not exist prior OMAP4 */
-        if (!cpu_is_omap44xx())
-                return -EINVAL;
-
-        if (!oh->clkdm || !oh->prcm.omap4.modulemode)
-                return -EINVAL;
-
-        pr_debug("omap_hwmod: %s: %s\n", oh->name, __func__);
-
-        omap4_cminst_module_disable(oh->clkdm->prcm_partition,
-                                    oh->clkdm->cm_inst,
-                                    oh->clkdm->clkdm_offs,
-                                    oh->prcm.omap4.clkctrl_offs);
-
-        v = _omap4_wait_target_disable(oh);
-        if (v)
-                pr_warn("omap_hwmod: %s: _wait_target_disable failed\n",
-                        oh->name);
-
-        return 0;
-}
-
-/**
  * _count_mpu_irqs - count the number of MPU IRQ lines associated with @oh
  * @oh: struct omap_hwmod *oh
  *
@@ -1378,6 +1345,66 @@ static int _read_hardreset(struct omap_hwmod *oh, const char *name)
 }
 
 /**
+ * _are_any_hardreset_lines_asserted - return true if part of @oh is hard-reset
+ * @oh: struct omap_hwmod *
+ *
+ * If any hardreset line associated with @oh is asserted, then return true.
+ * Otherwise, if @oh has no hardreset lines associated with it, or if
+ * no hardreset lines associated with @oh are asserted, then return false.
+ * This function is used to avoid executing some parts of the IP block
+ * enable/disable sequence if a hardreset line is set.
+ */
+static bool _are_any_hardreset_lines_asserted(struct omap_hwmod *oh)
+{
+        int i;
+
+        if (oh->rst_lines_cnt == 0)
+                return false;
+
+        for (i = 0; i < oh->rst_lines_cnt; i++)
+                if (_read_hardreset(oh, oh->rst_lines[i].name) > 0)
+                        return true;
+
+        return false;
+}
+
+/**
+ * _omap4_disable_module - enable CLKCTRL modulemode on OMAP4
+ * @oh: struct omap_hwmod *
+ *
+ * Disable the PRCM module mode related to the hwmod @oh.
+ * Return EINVAL if the modulemode is not supported and 0 in case of success.
+ */
+static int _omap4_disable_module(struct omap_hwmod *oh)
+{
+        int v;
+
+        /* The module mode does not exist prior OMAP4 */
+        if (!cpu_is_omap44xx())
+                return -EINVAL;
+
+        if (!oh->clkdm || !oh->prcm.omap4.modulemode)
+                return -EINVAL;
+
+        pr_debug("omap_hwmod: %s: %s\n", oh->name, __func__);
+
+        omap4_cminst_module_disable(oh->clkdm->prcm_partition,
+                                    oh->clkdm->cm_inst,
+                                    oh->clkdm->clkdm_offs,
+                                    oh->prcm.omap4.clkctrl_offs);
+
+        if (_are_any_hardreset_lines_asserted(oh))
+                return 0;
+
+        v = _omap4_wait_target_disable(oh);
+        if (v)
+                pr_warn("omap_hwmod: %s: _wait_target_disable failed\n",
+                        oh->name);
+
+        return 0;
+}
+
+/**
  * _ocp_softreset - reset an omap_hwmod via the OCP_SYSCONFIG bit
  * @oh: struct omap_hwmod *
  *
@@ -1528,7 +1555,7 @@ static int _reset(struct omap_hwmod *oh)
  */
 static int _enable(struct omap_hwmod *oh)
 {
-        int r, i;
+        int r;
         int hwsup = 0;
 
         pr_debug("omap_hwmod: %s: enabling\n", oh->name);
@@ -1560,14 +1587,16 @@ static int _enable(struct omap_hwmod *oh)
         }
 
         /*
-         * If an IP contains HW reset lines, then de-assert them in order
-         * to allow the module state transition. Otherwise the PRCM will return
-         * Intransition status, and the init will failed.
+         * If an IP block contains HW reset lines and any of them are
+         * asserted, we let integration code associated with that
+         * block handle the enable.  We've received very little
+         * information on what those driver authors need, and until
+         * detailed information is provided and the driver code is
+         * posted to the public lists, this is probably the best we
+         * can do.
          */
-        if (oh->_state == _HWMOD_STATE_INITIALIZED ||
-            oh->_state == _HWMOD_STATE_DISABLED)
-                for (i = 0; i < oh->rst_lines_cnt; i++)
-                        _deassert_hardreset(oh, oh->rst_lines[i].name);
+        if (_are_any_hardreset_lines_asserted(oh))
+                return 0;
 
         /* Mux pins for device runtime if populated */
         if (oh->mux && (!oh->mux->enabled ||
@@ -1642,6 +1671,9 @@ static int _idle(struct omap_hwmod *oh)
                 return -EINVAL;
         }
 
+        if (_are_any_hardreset_lines_asserted(oh))
+                return 0;
+
         if (oh->class->sysc)
                 _idle_sysc(oh);
         _del_initiator_dep(oh, mpu_oh);
@@ -1724,6 +1756,9 @@ static int _shutdown(struct omap_hwmod *oh)
                 return -EINVAL;
         }
 
+        if (_are_any_hardreset_lines_asserted(oh))
+                return 0;
+
         pr_debug("omap_hwmod: %s: disabling\n", oh->name);
 
         if (oh->class->pre_shutdown) {
@@ -1866,21 +1901,13 @@ static int __init _setup_reset(struct omap_hwmod *oh)
         if (oh->_state != _HWMOD_STATE_INITIALIZED)
                 return -EINVAL;
 
-        /*
-         * In the case of hwmod with hardreset that should not be
-         * de-assert at boot time, we have to keep the module
-         * initialized, because we cannot enable it properly with the
-         * reset asserted. Exit without warning because that behavior
-         * is expected.
-         */
-        if ((oh->flags & HWMOD_INIT_NO_RESET) && oh->rst_lines_cnt > 0)
-                return 0;
-
-        r = _enable(oh);
-        if (r) {
-                pr_warning("omap_hwmod: %s: cannot be enabled (%d)\n",
-                           oh->name, oh->_state);
-                return 0;
+        if (oh->rst_lines_cnt == 0) {
+                r = _enable(oh);
+                if (r) {
+                        pr_warning("omap_hwmod: %s: cannot be enabled for reset (%d)\n",
+                                   oh->name, oh->_state);
+                        return -EINVAL;
+                }
         }
 
         if (!(oh->flags & HWMOD_INIT_NO_RESET))