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authorAlex Elder <elder@linaro.org>2014-04-21 16:11:42 -0500
committerMike Turquette <mturquette@linaro.org>2014-04-30 11:51:36 -0700
commita597faccc7eedd406313e880ed05ff75bc522910 (patch)
tree4e463bcfde259380a3ea5b50534272357f007dc8 /drivers/clk/bcm/clk-kona.c
parent03548ec06ad3ec75d5b212fa832e4e617334ea09 (diff)
clk: bcm281xx: add clock policy support
Add support for CCU policy engine control, and also for setting the mask bits for bus clocks that require a policy change to get activated. This includes adding validity checking framework for CCUs, to validate the policy fields if defined. Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: Mike Turquette <mturquette@linaro.org>
Diffstat (limited to 'drivers/clk/bcm/clk-kona.c')
-rw-r--r--drivers/clk/bcm/clk-kona.c155
1 files changed, 155 insertions, 0 deletions
diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
index f8bc6bc0784f..7d90c34d1336 100644
--- a/drivers/clk/bcm/clk-kona.c
+++ b/drivers/clk/bcm/clk-kona.c
@@ -16,6 +16,14 @@
#include <linux/delay.h>
+/*
+ * "Policies" affect the frequencies of bus clocks provided by a
+ * CCU. (I believe these polices are named "Deep Sleep", "Economy",
+ * "Normal", and "Turbo".) A lower policy number has lower power
+ * consumption, and policy 2 is the default.
+ */
+#define CCU_POLICY_COUNT 4
+
#define CCU_ACCESS_PASSWORD 0xA5A500
#define CLK_GATE_DELAY_LOOP 2000
@@ -213,6 +221,148 @@ __ccu_wait_bit(struct ccu_data *ccu, u32 reg_offset, u32 bit, bool want)
return false;
}
+/* Policy operations */
+
+static bool __ccu_policy_engine_start(struct ccu_data *ccu, bool sync)
+{
+ struct bcm_policy_ctl *control = &ccu->policy.control;
+ u32 offset;
+ u32 go_bit;
+ u32 mask;
+ bool ret;
+
+ /* If we don't need to control policy for this CCU, we're done. */
+ if (!policy_ctl_exists(control))
+ return true;
+
+ offset = control->offset;
+ go_bit = control->go_bit;
+
+ /* Ensure we're not busy before we start */
+ ret = __ccu_wait_bit(ccu, offset, go_bit, false);
+ if (!ret) {
+ pr_err("%s: ccu %s policy engine wouldn't go idle\n",
+ __func__, ccu->name);
+ return false;
+ }
+
+ /*
+ * If it's a synchronous request, we'll wait for the voltage
+ * and frequency of the active load to stabilize before
+ * returning. To do this we select the active load by
+ * setting the ATL bit.
+ *
+ * An asynchronous request instead ramps the voltage in the
+ * background, and when that process stabilizes, the target
+ * load is copied to the active load and the CCU frequency
+ * is switched. We do this by selecting the target load
+ * (ATL bit clear) and setting the request auto-copy (AC bit
+ * set).
+ *
+ * Note, we do NOT read-modify-write this register.
+ */
+ mask = (u32)1 << go_bit;
+ if (sync)
+ mask |= 1 << control->atl_bit;
+ else
+ mask |= 1 << control->ac_bit;
+ __ccu_write(ccu, offset, mask);
+
+ /* Wait for indication that operation is complete. */
+ ret = __ccu_wait_bit(ccu, offset, go_bit, false);
+ if (!ret)
+ pr_err("%s: ccu %s policy engine never started\n",
+ __func__, ccu->name);
+
+ return ret;
+}
+
+static bool __ccu_policy_engine_stop(struct ccu_data *ccu)
+{
+ struct bcm_lvm_en *enable = &ccu->policy.enable;
+ u32 offset;
+ u32 enable_bit;
+ bool ret;
+
+ /* If we don't need to control policy for this CCU, we're done. */
+ if (!policy_lvm_en_exists(enable))
+ return true;
+
+ /* Ensure we're not busy before we start */
+ offset = enable->offset;
+ enable_bit = enable->bit;
+ ret = __ccu_wait_bit(ccu, offset, enable_bit, false);
+ if (!ret) {
+ pr_err("%s: ccu %s policy engine already stopped\n",
+ __func__, ccu->name);
+ return false;
+ }
+
+ /* Now set the bit to stop the engine (NO read-modify-write) */
+ __ccu_write(ccu, offset, (u32)1 << enable_bit);
+
+ /* Wait for indication that it has stopped. */
+ ret = __ccu_wait_bit(ccu, offset, enable_bit, false);
+ if (!ret)
+ pr_err("%s: ccu %s policy engine never stopped\n",
+ __func__, ccu->name);
+
+ return ret;
+}
+
+/*
+ * A CCU has four operating conditions ("policies"), and some clocks
+ * can be disabled or enabled based on which policy is currently in
+ * effect. Such clocks have a bit in a "policy mask" register for
+ * each policy indicating whether the clock is enabled for that
+ * policy or not. The bit position for a clock is the same for all
+ * four registers, and the 32-bit registers are at consecutive
+ * addresses.
+ */
+static bool policy_init(struct ccu_data *ccu, struct bcm_clk_policy *policy)
+{
+ u32 offset;
+ u32 mask;
+ int i;
+ bool ret;
+
+ if (!policy_exists(policy))
+ return true;
+
+ /*
+ * We need to stop the CCU policy engine to allow update
+ * of our policy bits.
+ */
+ if (!__ccu_policy_engine_stop(ccu)) {
+ pr_err("%s: unable to stop CCU %s policy engine\n",
+ __func__, ccu->name);
+ return false;
+ }
+
+ /*
+ * For now, if a clock defines its policy bit we just mark
+ * it "enabled" for all four policies.
+ */
+ offset = policy->offset;
+ mask = (u32)1 << policy->bit;
+ for (i = 0; i < CCU_POLICY_COUNT; i++) {
+ u32 reg_val;
+
+ reg_val = __ccu_read(ccu, offset);
+ reg_val |= mask;
+ __ccu_write(ccu, offset, reg_val);
+ offset += sizeof(u32);
+ }
+
+ /* We're done updating; fire up the policy engine again. */
+ ret = __ccu_policy_engine_start(ccu, true);
+ if (!ret)
+ pr_err("%s: unable to restart CCU %s policy engine\n",
+ __func__, ccu->name);
+
+ return ret;
+}
+
/* Gate operations */
/* Determine whether a clock is gated. CCU lock must be held. */
@@ -972,6 +1122,11 @@ static bool __peri_clk_init(struct kona_clk *bcm_clk)
BUG_ON(bcm_clk->type != bcm_clk_peri);
+ if (!policy_init(ccu, &peri->policy)) {
+ pr_err("%s: error initializing policy for %s\n",
+ __func__, name);
+ return false;
+ }
if (!gate_init(ccu, &peri->gate)) {
pr_err("%s: error initializing gate for %s\n", __func__, name);
return false;