ARM: omap: clk: add clk_prepare and clk_unprepare

As part of Common Clk Framework (CCF) the clk_enable() operation
was split into a clk_prepare() which could sleep, and a clk_enable()
which should never sleep. Similarly the clk_disable() was
split into clk_disable() and clk_unprepare(). This was
needed to handle complex cases where in a clk gate/ungate
would require a slow and a fast part to be implemented.
None of the clocks below seem to be in the 'complex' clocks
category and are just simple clocks which are enabled/disabled
through simple register writes.
Most of the instances also seem to be called in non-atomic
context which means its safe to move all of those from
using a clk_enable() to clk_prepare_enable() and clk_disable() to
clk_disable_unprepare().

For some others, mainly the ones handled through the hwmod framework
there is a possibility that they get called in either an atomic
or a non-atomic context.

The way these get handled below work only as long as clk_prepare
is implemented as a no-op (which is the case today) since this gets
called very early at boot while most subsystems are unavailable.
Hence these are marked with a *HACK* comment, which says we need
to re-visit these once we start doing something meaningful with
clk_prepare/clk_unprepare like doing voltage scaling or something
that involves i2c.

This is in preparation of OMAP moving to CCF.

Based on initial changes from Mike Turquette.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>

7 files changed, 40 insertions, 13 deletions

diff --git a/arch/arm/mach-omap2/board-apollon.c b/arch/arm/mach-omap2/board-apollon.c
index 3e2d76f05af4..cea3abace815 100644
--- a/arch/arm/mach-omap2/board-apollon.c
+++ b/arch/arm/mach-omap2/board-apollon.c
@@ -202,7 +202,7 @@ static inline void __init apollon_init_smc91x(void)
                 return;
         }
 
-        clk_enable(gpmc_fck);
+        clk_prepare_enable(gpmc_fck);
         rate = clk_get_rate(gpmc_fck);
 
         eth_cs = APOLLON_ETH_CS;
@@ -246,7 +246,7 @@ static inline void __init apollon_init_smc91x(void)
                 gpmc_cs_free(APOLLON_ETH_CS);
         }
 out:
-        clk_disable(gpmc_fck);
+        clk_disable_unprepare(gpmc_fck);
         clk_put(gpmc_fck);
 }
 
diff --git a/arch/arm/mach-omap2/board-h4.c b/arch/arm/mach-omap2/board-h4.c
index 12569cb0eddd..313b3f426a56 100644
--- a/arch/arm/mach-omap2/board-h4.c
+++ b/arch/arm/mach-omap2/board-h4.c
@@ -265,9 +265,9 @@ static inline void __init h4_init_debug(void)
                 return;
         }
 
-        clk_enable(gpmc_fck);
+        clk_prepare_enable(gpmc_fck);
         rate = clk_get_rate(gpmc_fck);
-        clk_disable(gpmc_fck);
+        clk_disable_unprepare(gpmc_fck);
         clk_put(gpmc_fck);
 
         if (is_gpmc_muxed())
@@ -311,7 +311,7 @@ static inline void __init h4_init_debug(void)
                 gpmc_cs_free(eth_cs);
 
 out:
-        clk_disable(gpmc_fck);
+        clk_disable_unprepare(gpmc_fck);
         clk_put(gpmc_fck);
 }
 
diff --git a/arch/arm/mach-omap2/board-omap4panda.c b/arch/arm/mach-omap2/board-omap4panda.c
index 45fe2d3f59b1..8ae2c599dd7f 100644
--- a/arch/arm/mach-omap2/board-omap4panda.c
+++ b/arch/arm/mach-omap2/board-omap4panda.c
@@ -171,7 +171,7 @@ static void __init omap4_ehci_init(void)
                 return;
         }
         clk_set_rate(phy_ref_clk, 19200000);
-        clk_enable(phy_ref_clk);
+        clk_prepare_enable(phy_ref_clk);
 
         /* disable the power to the usb hub prior to init and reset phy+hub */
         ret = gpio_request_array(panda_ehci_gpios,
diff --git a/arch/arm/mach-omap2/clock3xxx.c b/arch/arm/mach-omap2/clock3xxx.c
index fc2765bcdd40..319ff52220b8 100644
--- a/arch/arm/mach-omap2/clock3xxx.c
+++ b/arch/arm/mach-omap2/clock3xxx.c
@@ -64,15 +64,15 @@ void __init omap3_clk_lock_dpll5(void)
 
         dpll5_clk = clk_get(NULL, "dpll5_ck");
         clk_set_rate(dpll5_clk, DPLL5_FREQ_FOR_USBHOST);
-        clk_enable(dpll5_clk);
+        clk_prepare_enable(dpll5_clk);
 
         /* Program dpll5_m2_clk divider for no division */
         dpll5_m2_clk = clk_get(NULL, "dpll5_m2_ck");
-        clk_enable(dpll5_m2_clk);
+        clk_prepare_enable(dpll5_m2_clk);
         clk_set_rate(dpll5_m2_clk, DPLL5_FREQ_FOR_USBHOST);
 
-        clk_disable(dpll5_m2_clk);
-        clk_disable(dpll5_clk);
+        clk_disable_unprepare(dpll5_m2_clk);
+        clk_disable_unprepare(dpll5_clk);
         return;
 }
 
diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
index af1ed7d24a1f..5a3afd2b737d 100644
--- a/arch/arm/mach-omap2/display.c
+++ b/arch/arm/mach-omap2/display.c
@@ -488,7 +488,7 @@ int omap_dss_reset(struct omap_hwmod *oh)
 
         for (i = oh->opt_clks_cnt, oc = oh->opt_clks; i > 0; i--, oc++)
                 if (oc->_clk)
-                        clk_enable(oc->_clk);
+                        clk_prepare_enable(oc->_clk);
 
         dispc_disable_outputs();
 
@@ -515,7 +515,7 @@ int omap_dss_reset(struct omap_hwmod *oh)
 
         for (i = oh->opt_clks_cnt, oc = oh->opt_clks; i > 0; i--, oc++)
                 if (oc->_clk)
-                        clk_disable(oc->_clk);
+                        clk_disable_unprepare(oc->_clk);
 
         r = (c == MAX_MODULE_SOFTRESET_WAIT) ? -ETIMEDOUT : 0;
 
diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index 055ae8bd943f..5de0f7b852f7 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/arch/arm/mach-omap2/gpmc.c
@@ -879,7 +879,7 @@ static int __init gpmc_init(void)
                 BUG();
         }
 
-        clk_enable(gpmc_l3_clk);
+        clk_prepare_enable(gpmc_l3_clk);
 
         l = gpmc_read_reg(GPMC_REVISION);
         printk(KERN_INFO "GPMC revision %d.%d\n", (l >> 4) & 0x0f, l & 0x0f);
diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 6504f0e8d96e..99fd3bb3c432 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -685,6 +685,15 @@ static int _init_main_clk(struct omap_hwmod *oh)
                            oh->name, oh->main_clk);
                 return -EINVAL;
         }
+        /*
+         * HACK: This needs a re-visit once clk_prepare() is implemented
+         * to do something meaningful. Today its just a no-op.
+         * If clk_prepare() is used at some point to do things like
+         * voltage scaling etc, then this would have to be moved to
+         * some point where subsystems like i2c and pmic become
+         * available.
+         */
+        clk_prepare(oh->_clk);
 
         if (!oh->_clk->clkdm)
                 pr_warning("omap_hwmod: %s: missing clockdomain for %s.\n",
@@ -722,6 +731,15 @@ static int _init_interface_clks(struct omap_hwmod *oh)
                         ret = -EINVAL;
                 }
                 os->_clk = c;
+                /*
+                 * HACK: This needs a re-visit once clk_prepare() is implemented
+                 * to do something meaningful. Today its just a no-op.
+                 * If clk_prepare() is used at some point to do things like
+                 * voltage scaling etc, then this would have to be moved to
+                 * some point where subsystems like i2c and pmic become
+                 * available.
+                 */
+                clk_prepare(os->_clk);
         }
 
         return ret;
@@ -749,6 +767,15 @@ static int _init_opt_clks(struct omap_hwmod *oh)
                         ret = -EINVAL;
                 }
                 oc->_clk = c;
+                /*
+                 * HACK: This needs a re-visit once clk_prepare() is implemented
+                 * to do something meaningful. Today its just a no-op.
+                 * If clk_prepare() is used at some point to do things like
+                 * voltage scaling etc, then this would have to be moved to
+                 * some point where subsystems like i2c and pmic become
+                 * available.
+                 */
+                clk_prepare(oc->_clk);
         }
 
         return ret;