diff options
Diffstat (limited to 'drivers/clk/bcm/clk-kona.c')
| -rw-r--r-- | drivers/clk/bcm/clk-kona.c | 155 |
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; |