diff options
Diffstat (limited to 'drivers/clk/bcm/clk-kona.c')
| -rw-r--r-- | drivers/clk/bcm/clk-kona.c | 1278 |
1 files changed, 1278 insertions, 0 deletions
diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c new file mode 100644 index 000000000..cc3b1e1bc --- /dev/null +++ b/drivers/clk/bcm/clk-kona.c @@ -0,0 +1,1278 @@ +/* + * Copyright (C) 2013 Broadcom Corporation + * Copyright 2013 Linaro Limited + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation version 2. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include "clk-kona.h" + +#include <linux/delay.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/clk-provider.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 + +/* Bitfield operations */ + +/* Produces a mask of set bits covering a range of a 32-bit value */ +static inline u32 bitfield_mask(u32 shift, u32 width) +{ + return ((1 << width) - 1) << shift; +} + +/* Extract the value of a bitfield found within a given register value */ +static inline u32 bitfield_extract(u32 reg_val, u32 shift, u32 width) +{ + return (reg_val & bitfield_mask(shift, width)) >> shift; +} + +/* Replace the value of a bitfield found within a given register value */ +static inline u32 bitfield_replace(u32 reg_val, u32 shift, u32 width, u32 val) +{ + u32 mask = bitfield_mask(shift, width); + + return (reg_val & ~mask) | (val << shift); +} + +/* Divider and scaling helpers */ + +/* Convert a divider into the scaled divisor value it represents. */ +static inline u64 scaled_div_value(struct bcm_clk_div *div, u32 reg_div) +{ + return (u64)reg_div + ((u64)1 << div->u.s.frac_width); +} + +/* + * Build a scaled divider value as close as possible to the + * given whole part (div_value) and fractional part (expressed + * in billionths). + */ +u64 scaled_div_build(struct bcm_clk_div *div, u32 div_value, u32 billionths) +{ + u64 combined; + + BUG_ON(!div_value); + BUG_ON(billionths >= BILLION); + + combined = (u64)div_value * BILLION + billionths; + combined <<= div->u.s.frac_width; + + return DIV_ROUND_CLOSEST_ULL(combined, BILLION); +} + +/* The scaled minimum divisor representable by a divider */ +static inline u64 +scaled_div_min(struct bcm_clk_div *div) +{ + if (divider_is_fixed(div)) + return (u64)div->u.fixed; + + return scaled_div_value(div, 0); +} + +/* The scaled maximum divisor representable by a divider */ +u64 scaled_div_max(struct bcm_clk_div *div) +{ + u32 reg_div; + + if (divider_is_fixed(div)) + return (u64)div->u.fixed; + + reg_div = ((u32)1 << div->u.s.width) - 1; + + return scaled_div_value(div, reg_div); +} + +/* + * Convert a scaled divisor into its divider representation as + * stored in a divider register field. + */ +static inline u32 +divider(struct bcm_clk_div *div, u64 scaled_div) +{ + BUG_ON(scaled_div < scaled_div_min(div)); + BUG_ON(scaled_div > scaled_div_max(div)); + + return (u32)(scaled_div - ((u64)1 << div->u.s.frac_width)); +} + +/* Return a rate scaled for use when dividing by a scaled divisor. */ +static inline u64 +scale_rate(struct bcm_clk_div *div, u32 rate) +{ + if (divider_is_fixed(div)) + return (u64)rate; + + return (u64)rate << div->u.s.frac_width; +} + +/* CCU access */ + +/* Read a 32-bit register value from a CCU's address space. */ +static inline u32 __ccu_read(struct ccu_data *ccu, u32 reg_offset) +{ + return readl(ccu->base + reg_offset); +} + +/* Write a 32-bit register value into a CCU's address space. */ +static inline void +__ccu_write(struct ccu_data *ccu, u32 reg_offset, u32 reg_val) +{ + writel(reg_val, ccu->base + reg_offset); +} + +static inline unsigned long ccu_lock(struct ccu_data *ccu) +{ + unsigned long flags; + + spin_lock_irqsave(&ccu->lock, flags); + + return flags; +} +static inline void ccu_unlock(struct ccu_data *ccu, unsigned long flags) +{ + spin_unlock_irqrestore(&ccu->lock, flags); +} + +/* + * Enable/disable write access to CCU protected registers. The + * WR_ACCESS register for all CCUs is at offset 0. + */ +static inline void __ccu_write_enable(struct ccu_data *ccu) +{ + if (ccu->write_enabled) { + pr_err("%s: access already enabled for %s\n", __func__, + ccu->name); + return; + } + ccu->write_enabled = true; + __ccu_write(ccu, 0, CCU_ACCESS_PASSWORD | 1); +} + +static inline void __ccu_write_disable(struct ccu_data *ccu) +{ + if (!ccu->write_enabled) { + pr_err("%s: access wasn't enabled for %s\n", __func__, + ccu->name); + return; + } + + __ccu_write(ccu, 0, CCU_ACCESS_PASSWORD); + ccu->write_enabled = false; +} + +/* + * Poll a register in a CCU's address space, returning when the + * specified bit in that register's value is set (or clear). Delay + * a microsecond after each read of the register. Returns true if + * successful, or false if we gave up trying. + * + * Caller must ensure the CCU lock is held. + */ +static inline bool +__ccu_wait_bit(struct ccu_data *ccu, u32 reg_offset, u32 bit, bool want) +{ + unsigned int tries; + u32 bit_mask = 1 << bit; + + for (tries = 0; tries < CLK_GATE_DELAY_LOOP; tries++) { + u32 val; + bool bit_val; + + val = __ccu_read(ccu, reg_offset); + bit_val = (val & bit_mask) != 0; + if (bit_val == want) + return true; + udelay(1); + } + pr_warn("%s: %s/0x%04x bit %u was never %s\n", __func__, + ccu->name, reg_offset, bit, want ? "set" : "clear"); + + 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. */ +static bool +__is_clk_gate_enabled(struct ccu_data *ccu, struct bcm_clk_gate *gate) +{ + u32 bit_mask; + u32 reg_val; + + /* If there is no gate we can assume it's enabled. */ + if (!gate_exists(gate)) + return true; + + bit_mask = 1 << gate->status_bit; + reg_val = __ccu_read(ccu, gate->offset); + + return (reg_val & bit_mask) != 0; +} + +/* Determine whether a clock is gated. */ +static bool +is_clk_gate_enabled(struct ccu_data *ccu, struct bcm_clk_gate *gate) +{ + long flags; + bool ret; + + /* Avoid taking the lock if we can */ + if (!gate_exists(gate)) + return true; + + flags = ccu_lock(ccu); + ret = __is_clk_gate_enabled(ccu, gate); + ccu_unlock(ccu, flags); + + return ret; +} + +/* + * Commit our desired gate state to the hardware. + * Returns true if successful, false otherwise. + */ +static bool +__gate_commit(struct ccu_data *ccu, struct bcm_clk_gate *gate) +{ + u32 reg_val; + u32 mask; + bool enabled = false; + + BUG_ON(!gate_exists(gate)); + if (!gate_is_sw_controllable(gate)) + return true; /* Nothing we can change */ + + reg_val = __ccu_read(ccu, gate->offset); + + /* For a hardware/software gate, set which is in control */ + if (gate_is_hw_controllable(gate)) { + mask = (u32)1 << gate->hw_sw_sel_bit; + if (gate_is_sw_managed(gate)) + reg_val |= mask; + else + reg_val &= ~mask; + } + + /* + * If software is in control, enable or disable the gate. + * If hardware is, clear the enabled bit for good measure. + * If a software controlled gate can't be disabled, we're + * required to write a 0 into the enable bit (but the gate + * will be enabled). + */ + mask = (u32)1 << gate->en_bit; + if (gate_is_sw_managed(gate) && (enabled = gate_is_enabled(gate)) && + !gate_is_no_disable(gate)) + reg_val |= mask; + else + reg_val &= ~mask; + + __ccu_write(ccu, gate->offset, reg_val); + + /* For a hardware controlled gate, we're done */ + if (!gate_is_sw_managed(gate)) + return true; + + /* Otherwise wait for the gate to be in desired state */ + return __ccu_wait_bit(ccu, gate->offset, gate->status_bit, enabled); +} + +/* + * Initialize a gate. Our desired state (hardware/software select, + * and if software, its enable state) is committed to hardware + * without the usual checks to see if it's already set up that way. + * Returns true if successful, false otherwise. + */ +static bool gate_init(struct ccu_data *ccu, struct bcm_clk_gate *gate) +{ + if (!gate_exists(gate)) + return true; + return __gate_commit(ccu, gate); +} + +/* + * Set a gate to enabled or disabled state. Does nothing if the + * gate is not currently under software control, or if it is already + * in the requested state. Returns true if successful, false + * otherwise. CCU lock must be held. + */ +static bool +__clk_gate(struct ccu_data *ccu, struct bcm_clk_gate *gate, bool enable) +{ + bool ret; + + if (!gate_exists(gate) || !gate_is_sw_managed(gate)) + return true; /* Nothing to do */ + + if (!enable && gate_is_no_disable(gate)) { + pr_warn("%s: invalid gate disable request (ignoring)\n", + __func__); + return true; + } + + if (enable == gate_is_enabled(gate)) + return true; /* No change */ + + gate_flip_enabled(gate); + ret = __gate_commit(ccu, gate); + if (!ret) + gate_flip_enabled(gate); /* Revert the change */ + + return ret; +} + +/* Enable or disable a gate. Returns 0 if successful, -EIO otherwise */ +static int clk_gate(struct ccu_data *ccu, const char *name, + struct bcm_clk_gate *gate, bool enable) +{ + unsigned long flags; + bool success; + + /* + * Avoid taking the lock if we can. We quietly ignore + * requests to change state that don't make sense. + */ + if (!gate_exists(gate) || !gate_is_sw_managed(gate)) + return 0; + if (!enable && gate_is_no_disable(gate)) + return 0; + + flags = ccu_lock(ccu); + __ccu_write_enable(ccu); + + success = __clk_gate(ccu, gate, enable); + + __ccu_write_disable(ccu); + ccu_unlock(ccu, flags); + + if (success) + return 0; + + pr_err("%s: failed to %s gate for %s\n", __func__, + enable ? "enable" : "disable", name); + + return -EIO; +} + +/* Hysteresis operations */ + +/* + * If a clock gate requires a turn-off delay it will have + * "hysteresis" register bits defined. The first, if set, enables + * the delay; and if enabled, the second bit determines whether the + * delay is "low" or "high" (1 means high). For now, if it's + * defined for a clock, we set it. + */ +static bool hyst_init(struct ccu_data *ccu, struct bcm_clk_hyst *hyst) +{ + u32 offset; + u32 reg_val; + u32 mask; + + if (!hyst_exists(hyst)) + return true; + + offset = hyst->offset; + mask = (u32)1 << hyst->en_bit; + mask |= (u32)1 << hyst->val_bit; + + reg_val = __ccu_read(ccu, offset); + reg_val |= mask; + __ccu_write(ccu, offset, reg_val); + + return true; +} + +/* Trigger operations */ + +/* + * Caller must ensure CCU lock is held and access is enabled. + * Returns true if successful, false otherwise. + */ +static bool __clk_trigger(struct ccu_data *ccu, struct bcm_clk_trig *trig) +{ + /* Trigger the clock and wait for it to finish */ + __ccu_write(ccu, trig->offset, 1 << trig->bit); + + return __ccu_wait_bit(ccu, trig->offset, trig->bit, false); +} + +/* Divider operations */ + +/* Read a divider value and return the scaled divisor it represents. */ +static u64 divider_read_scaled(struct ccu_data *ccu, struct bcm_clk_div *div) +{ + unsigned long flags; + u32 reg_val; + u32 reg_div; + + if (divider_is_fixed(div)) + return (u64)div->u.fixed; + + flags = ccu_lock(ccu); + reg_val = __ccu_read(ccu, div->u.s.offset); + ccu_unlock(ccu, flags); + + /* Extract the full divider field from the register value */ + reg_div = bitfield_extract(reg_val, div->u.s.shift, div->u.s.width); + + /* Return the scaled divisor value it represents */ + return scaled_div_value(div, reg_div); +} + +/* + * Convert a divider's scaled divisor value into its recorded form + * and commit it into the hardware divider register. + * + * Returns 0 on success. Returns -EINVAL for invalid arguments. + * Returns -ENXIO if gating failed, and -EIO if a trigger failed. + */ +static int __div_commit(struct ccu_data *ccu, struct bcm_clk_gate *gate, + struct bcm_clk_div *div, struct bcm_clk_trig *trig) +{ + bool enabled; + u32 reg_div; + u32 reg_val; + int ret = 0; + + BUG_ON(divider_is_fixed(div)); + + /* + * If we're just initializing the divider, and no initial + * state was defined in the device tree, we just find out + * what its current value is rather than updating it. + */ + if (div->u.s.scaled_div == BAD_SCALED_DIV_VALUE) { + reg_val = __ccu_read(ccu, div->u.s.offset); + reg_div = bitfield_extract(reg_val, div->u.s.shift, + div->u.s.width); + div->u.s.scaled_div = scaled_div_value(div, reg_div); + + return 0; + } + + /* Convert the scaled divisor to the value we need to record */ + reg_div = divider(div, div->u.s.scaled_div); + + /* Clock needs to be enabled before changing the rate */ + enabled = __is_clk_gate_enabled(ccu, gate); + if (!enabled && !__clk_gate(ccu, gate, true)) { + ret = -ENXIO; + goto out; + } + + /* Replace the divider value and record the result */ + reg_val = __ccu_read(ccu, div->u.s.offset); + reg_val = bitfield_replace(reg_val, div->u.s.shift, div->u.s.width, + reg_div); + __ccu_write(ccu, div->u.s.offset, reg_val); + + /* If the trigger fails we still want to disable the gate */ + if (!__clk_trigger(ccu, trig)) + ret = -EIO; + + /* Disable the clock again if it was disabled to begin with */ + if (!enabled && !__clk_gate(ccu, gate, false)) + ret = ret ? ret : -ENXIO; /* return first error */ +out: + return ret; +} + +/* + * Initialize a divider by committing our desired state to hardware + * without the usual checks to see if it's already set up that way. + * Returns true if successful, false otherwise. + */ +static bool div_init(struct ccu_data *ccu, struct bcm_clk_gate *gate, + struct bcm_clk_div *div, struct bcm_clk_trig *trig) +{ + if (!divider_exists(div) || divider_is_fixed(div)) + return true; + return !__div_commit(ccu, gate, div, trig); +} + +static int divider_write(struct ccu_data *ccu, struct bcm_clk_gate *gate, + struct bcm_clk_div *div, struct bcm_clk_trig *trig, + u64 scaled_div) +{ + unsigned long flags; + u64 previous; + int ret; + + BUG_ON(divider_is_fixed(div)); + + previous = div->u.s.scaled_div; + if (previous == scaled_div) + return 0; /* No change */ + + div->u.s.scaled_div = scaled_div; + + flags = ccu_lock(ccu); + __ccu_write_enable(ccu); + + ret = __div_commit(ccu, gate, div, trig); + + __ccu_write_disable(ccu); + ccu_unlock(ccu, flags); + + if (ret) + div->u.s.scaled_div = previous; /* Revert the change */ + + return ret; + +} + +/* Common clock rate helpers */ + +/* + * Implement the common clock framework recalc_rate method, taking + * into account a divider and an optional pre-divider. The + * pre-divider register pointer may be NULL. + */ +static unsigned long clk_recalc_rate(struct ccu_data *ccu, + struct bcm_clk_div *div, struct bcm_clk_div *pre_div, + unsigned long parent_rate) +{ + u64 scaled_parent_rate; + u64 scaled_div; + u64 result; + + if (!divider_exists(div)) + return parent_rate; + + if (parent_rate > (unsigned long)LONG_MAX) + return 0; /* actually this would be a caller bug */ + + /* + * If there is a pre-divider, divide the scaled parent rate + * by the pre-divider value first. In this case--to improve + * accuracy--scale the parent rate by *both* the pre-divider + * value and the divider before actually computing the + * result of the pre-divider. + * + * If there's only one divider, just scale the parent rate. + */ + if (pre_div && divider_exists(pre_div)) { + u64 scaled_rate; + + scaled_rate = scale_rate(pre_div, parent_rate); + scaled_rate = scale_rate(div, scaled_rate); + scaled_div = divider_read_scaled(ccu, pre_div); + scaled_parent_rate = DIV_ROUND_CLOSEST_ULL(scaled_rate, + scaled_div); + } else { + scaled_parent_rate = scale_rate(div, parent_rate); + } + + /* + * Get the scaled divisor value, and divide the scaled + * parent rate by that to determine this clock's resulting + * rate. + */ + scaled_div = divider_read_scaled(ccu, div); + result = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate, scaled_div); + + return (unsigned long)result; +} + +/* + * Compute the output rate produced when a given parent rate is fed + * into two dividers. The pre-divider can be NULL, and even if it's + * non-null it may be nonexistent. It's also OK for the divider to + * be nonexistent, and in that case the pre-divider is also ignored. + * + * If scaled_div is non-null, it is used to return the scaled divisor + * value used by the (downstream) divider to produce that rate. + */ +static long round_rate(struct ccu_data *ccu, struct bcm_clk_div *div, + struct bcm_clk_div *pre_div, + unsigned long rate, unsigned long parent_rate, + u64 *scaled_div) +{ + u64 scaled_parent_rate; + u64 min_scaled_div; + u64 max_scaled_div; + u64 best_scaled_div; + u64 result; + + BUG_ON(!divider_exists(div)); + BUG_ON(!rate); + BUG_ON(parent_rate > (u64)LONG_MAX); + + /* + * If there is a pre-divider, divide the scaled parent rate + * by the pre-divider value first. In this case--to improve + * accuracy--scale the parent rate by *both* the pre-divider + * value and the divider before actually computing the + * result of the pre-divider. + * + * If there's only one divider, just scale the parent rate. + * + * For simplicity we treat the pre-divider as fixed (for now). + */ + if (divider_exists(pre_div)) { + u64 scaled_rate; + u64 scaled_pre_div; + + scaled_rate = scale_rate(pre_div, parent_rate); + scaled_rate = scale_rate(div, scaled_rate); + scaled_pre_div = divider_read_scaled(ccu, pre_div); + scaled_parent_rate = DIV_ROUND_CLOSEST_ULL(scaled_rate, + scaled_pre_div); + } else { + scaled_parent_rate = scale_rate(div, parent_rate); + } + + /* + * Compute the best possible divider and ensure it is in + * range. A fixed divider can't be changed, so just report + * the best we can do. + */ + if (!divider_is_fixed(div)) { + best_scaled_div = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate, + rate); + min_scaled_div = scaled_div_min(div); + max_scaled_div = scaled_div_max(div); + if (best_scaled_div > max_scaled_div) + best_scaled_div = max_scaled_div; + else if (best_scaled_div < min_scaled_div) + best_scaled_div = min_scaled_div; + } else { + best_scaled_div = divider_read_scaled(ccu, div); + } + + /* OK, figure out the resulting rate */ + result = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate, best_scaled_div); + + if (scaled_div) + *scaled_div = best_scaled_div; + + return (long)result; +} + +/* Common clock parent helpers */ + +/* + * For a given parent selector (register field) value, find the + * index into a selector's parent_sel array that contains it. + * Returns the index, or BAD_CLK_INDEX if it's not found. + */ +static u8 parent_index(struct bcm_clk_sel *sel, u8 parent_sel) +{ + u8 i; + + BUG_ON(sel->parent_count > (u32)U8_MAX); + for (i = 0; i < sel->parent_count; i++) + if (sel->parent_sel[i] == parent_sel) + return i; + return BAD_CLK_INDEX; +} + +/* + * Fetch the current value of the selector, and translate that into + * its corresponding index in the parent array we registered with + * the clock framework. + * + * Returns parent array index that corresponds with the value found, + * or BAD_CLK_INDEX if the found value is out of range. + */ +static u8 selector_read_index(struct ccu_data *ccu, struct bcm_clk_sel *sel) +{ + unsigned long flags; + u32 reg_val; + u32 parent_sel; + u8 index; + + /* If there's no selector, there's only one parent */ + if (!selector_exists(sel)) + return 0; + + /* Get the value in the selector register */ + flags = ccu_lock(ccu); + reg_val = __ccu_read(ccu, sel->offset); + ccu_unlock(ccu, flags); + + parent_sel = bitfield_extract(reg_val, sel->shift, sel->width); + + /* Look up that selector's parent array index and return it */ + index = parent_index(sel, parent_sel); + if (index == BAD_CLK_INDEX) + pr_err("%s: out-of-range parent selector %u (%s 0x%04x)\n", + __func__, parent_sel, ccu->name, sel->offset); + + return index; +} + +/* + * Commit our desired selector value to the hardware. + * + * Returns 0 on success. Returns -EINVAL for invalid arguments. + * Returns -ENXIO if gating failed, and -EIO if a trigger failed. + */ +static int +__sel_commit(struct ccu_data *ccu, struct bcm_clk_gate *gate, + struct bcm_clk_sel *sel, struct bcm_clk_trig *trig) +{ + u32 parent_sel; + u32 reg_val; + bool enabled; + int ret = 0; + + BUG_ON(!selector_exists(sel)); + + /* + * If we're just initializing the selector, and no initial + * state was defined in the device tree, we just find out + * what its current value is rather than updating it. + */ + if (sel->clk_index == BAD_CLK_INDEX) { + u8 index; + + reg_val = __ccu_read(ccu, sel->offset); + parent_sel = bitfield_extract(reg_val, sel->shift, sel->width); + index = parent_index(sel, parent_sel); + if (index == BAD_CLK_INDEX) + return -EINVAL; + sel->clk_index = index; + + return 0; + } + + BUG_ON((u32)sel->clk_index >= sel->parent_count); + parent_sel = sel->parent_sel[sel->clk_index]; + + /* Clock needs to be enabled before changing the parent */ + enabled = __is_clk_gate_enabled(ccu, gate); + if (!enabled && !__clk_gate(ccu, gate, true)) + return -ENXIO; + + /* Replace the selector value and record the result */ + reg_val = __ccu_read(ccu, sel->offset); + reg_val = bitfield_replace(reg_val, sel->shift, sel->width, parent_sel); + __ccu_write(ccu, sel->offset, reg_val); + + /* If the trigger fails we still want to disable the gate */ + if (!__clk_trigger(ccu, trig)) + ret = -EIO; + + /* Disable the clock again if it was disabled to begin with */ + if (!enabled && !__clk_gate(ccu, gate, false)) + ret = ret ? ret : -ENXIO; /* return first error */ + + return ret; +} + +/* + * Initialize a selector by committing our desired state to hardware + * without the usual checks to see if it's already set up that way. + * Returns true if successful, false otherwise. + */ +static bool sel_init(struct ccu_data *ccu, struct bcm_clk_gate *gate, + struct bcm_clk_sel *sel, struct bcm_clk_trig *trig) +{ + if (!selector_exists(sel)) + return true; + return !__sel_commit(ccu, gate, sel, trig); +} + +/* + * Write a new value into a selector register to switch to a + * different parent clock. Returns 0 on success, or an error code + * (from __sel_commit()) otherwise. + */ +static int selector_write(struct ccu_data *ccu, struct bcm_clk_gate *gate, + struct bcm_clk_sel *sel, struct bcm_clk_trig *trig, + u8 index) +{ + unsigned long flags; + u8 previous; + int ret; + + previous = sel->clk_index; + if (previous == index) + return 0; /* No change */ + + sel->clk_index = index; + + flags = ccu_lock(ccu); + __ccu_write_enable(ccu); + + ret = __sel_commit(ccu, gate, sel, trig); + + __ccu_write_disable(ccu); + ccu_unlock(ccu, flags); + + if (ret) + sel->clk_index = previous; /* Revert the change */ + + return ret; +} + +/* Clock operations */ + +static int kona_peri_clk_enable(struct clk_hw *hw) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct bcm_clk_gate *gate = &bcm_clk->u.peri->gate; + + return clk_gate(bcm_clk->ccu, bcm_clk->init_data.name, gate, true); +} + +static void kona_peri_clk_disable(struct clk_hw *hw) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct bcm_clk_gate *gate = &bcm_clk->u.peri->gate; + + (void)clk_gate(bcm_clk->ccu, bcm_clk->init_data.name, gate, false); +} + +static int kona_peri_clk_is_enabled(struct clk_hw *hw) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct bcm_clk_gate *gate = &bcm_clk->u.peri->gate; + + return is_clk_gate_enabled(bcm_clk->ccu, gate) ? 1 : 0; +} + +static unsigned long kona_peri_clk_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct peri_clk_data *data = bcm_clk->u.peri; + + return clk_recalc_rate(bcm_clk->ccu, &data->div, &data->pre_div, + parent_rate); +} + +static long kona_peri_clk_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct bcm_clk_div *div = &bcm_clk->u.peri->div; + + if (!divider_exists(div)) + return clk_hw_get_rate(hw); + + /* Quietly avoid a zero rate */ + return round_rate(bcm_clk->ccu, div, &bcm_clk->u.peri->pre_div, + rate ? rate : 1, *parent_rate, NULL); +} + +static int kona_peri_clk_determine_rate(struct clk_hw *hw, + struct clk_rate_request *req) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct clk_hw *current_parent; + unsigned long parent_rate; + unsigned long best_delta; + unsigned long best_rate; + u32 parent_count; + long rate; + u32 which; + + /* + * If there is no other parent to choose, use the current one. + * Note: We don't honor (or use) CLK_SET_RATE_NO_REPARENT. + */ + WARN_ON_ONCE(bcm_clk->init_data.flags & CLK_SET_RATE_NO_REPARENT); + parent_count = (u32)bcm_clk->init_data.num_parents; + if (parent_count < 2) { + rate = kona_peri_clk_round_rate(hw, req->rate, + &req->best_parent_rate); + if (rate < 0) + return rate; + + req->rate = rate; + return 0; + } + + /* Unless we can do better, stick with current parent */ + current_parent = clk_hw_get_parent(hw); + parent_rate = clk_hw_get_rate(current_parent); + best_rate = kona_peri_clk_round_rate(hw, req->rate, &parent_rate); + best_delta = abs(best_rate - req->rate); + + /* Check whether any other parent clock can produce a better result */ + for (which = 0; which < parent_count; which++) { + struct clk_hw *parent = clk_hw_get_parent_by_index(hw, which); + unsigned long delta; + unsigned long other_rate; + + BUG_ON(!parent); + if (parent == current_parent) + continue; + + /* We don't support CLK_SET_RATE_PARENT */ + parent_rate = clk_hw_get_rate(parent); + other_rate = kona_peri_clk_round_rate(hw, req->rate, + &parent_rate); + delta = abs(other_rate - req->rate); + if (delta < best_delta) { + best_delta = delta; + best_rate = other_rate; + req->best_parent_hw = parent; + req->best_parent_rate = parent_rate; + } + } + + req->rate = best_rate; + return 0; +} + +static int kona_peri_clk_set_parent(struct clk_hw *hw, u8 index) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct peri_clk_data *data = bcm_clk->u.peri; + struct bcm_clk_sel *sel = &data->sel; + struct bcm_clk_trig *trig; + int ret; + + BUG_ON(index >= sel->parent_count); + + /* If there's only one parent we don't require a selector */ + if (!selector_exists(sel)) + return 0; + + /* + * The regular trigger is used by default, but if there's a + * pre-trigger we want to use that instead. + */ + trig = trigger_exists(&data->pre_trig) ? &data->pre_trig + : &data->trig; + + ret = selector_write(bcm_clk->ccu, &data->gate, sel, trig, index); + if (ret == -ENXIO) { + pr_err("%s: gating failure for %s\n", __func__, + bcm_clk->init_data.name); + ret = -EIO; /* Don't proliferate weird errors */ + } else if (ret == -EIO) { + pr_err("%s: %strigger failed for %s\n", __func__, + trig == &data->pre_trig ? "pre-" : "", + bcm_clk->init_data.name); + } + + return ret; +} + +static u8 kona_peri_clk_get_parent(struct clk_hw *hw) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct peri_clk_data *data = bcm_clk->u.peri; + u8 index; + + index = selector_read_index(bcm_clk->ccu, &data->sel); + + /* Not all callers would handle an out-of-range value gracefully */ + return index == BAD_CLK_INDEX ? 0 : index; +} + +static int kona_peri_clk_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct peri_clk_data *data = bcm_clk->u.peri; + struct bcm_clk_div *div = &data->div; + u64 scaled_div = 0; + int ret; + + if (parent_rate > (unsigned long)LONG_MAX) + return -EINVAL; + + if (rate == clk_hw_get_rate(hw)) + return 0; + + if (!divider_exists(div)) + return rate == parent_rate ? 0 : -EINVAL; + + /* + * A fixed divider can't be changed. (Nor can a fixed + * pre-divider be, but for now we never actually try to + * change that.) Tolerate a request for a no-op change. + */ + if (divider_is_fixed(&data->div)) + return rate == parent_rate ? 0 : -EINVAL; + + /* + * Get the scaled divisor value needed to achieve a clock + * rate as close as possible to what was requested, given + * the parent clock rate supplied. + */ + (void)round_rate(bcm_clk->ccu, div, &data->pre_div, + rate ? rate : 1, parent_rate, &scaled_div); + + /* + * We aren't updating any pre-divider at this point, so + * we'll use the regular trigger. + */ + ret = divider_write(bcm_clk->ccu, &data->gate, &data->div, + &data->trig, scaled_div); + if (ret == -ENXIO) { + pr_err("%s: gating failure for %s\n", __func__, + bcm_clk->init_data.name); + ret = -EIO; /* Don't proliferate weird errors */ + } else if (ret == -EIO) { + pr_err("%s: trigger failed for %s\n", __func__, + bcm_clk->init_data.name); + } + + return ret; +} + +struct clk_ops kona_peri_clk_ops = { + .enable = kona_peri_clk_enable, + .disable = kona_peri_clk_disable, + .is_enabled = kona_peri_clk_is_enabled, + .recalc_rate = kona_peri_clk_recalc_rate, + .determine_rate = kona_peri_clk_determine_rate, + .set_parent = kona_peri_clk_set_parent, + .get_parent = kona_peri_clk_get_parent, + .set_rate = kona_peri_clk_set_rate, +}; + +/* Put a peripheral clock into its initial state */ +static bool __peri_clk_init(struct kona_clk *bcm_clk) +{ + struct ccu_data *ccu = bcm_clk->ccu; + struct peri_clk_data *peri = bcm_clk->u.peri; + const char *name = bcm_clk->init_data.name; + struct bcm_clk_trig *trig; + + 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; + } + if (!hyst_init(ccu, &peri->hyst)) { + pr_err("%s: error initializing hyst for %s\n", __func__, name); + return false; + } + if (!div_init(ccu, &peri->gate, &peri->div, &peri->trig)) { + pr_err("%s: error initializing divider for %s\n", __func__, + name); + return false; + } + + /* + * For the pre-divider and selector, the pre-trigger is used + * if it's present, otherwise we just use the regular trigger. + */ + trig = trigger_exists(&peri->pre_trig) ? &peri->pre_trig + : &peri->trig; + + if (!div_init(ccu, &peri->gate, &peri->pre_div, trig)) { + pr_err("%s: error initializing pre-divider for %s\n", __func__, + name); + return false; + } + + if (!sel_init(ccu, &peri->gate, &peri->sel, trig)) { + pr_err("%s: error initializing selector for %s\n", __func__, + name); + return false; + } + + return true; +} + +static bool __kona_clk_init(struct kona_clk *bcm_clk) +{ + switch (bcm_clk->type) { + case bcm_clk_peri: + return __peri_clk_init(bcm_clk); + default: + BUG(); + } + return false; +} + +/* Set a CCU and all its clocks into their desired initial state */ +bool __init kona_ccu_init(struct ccu_data *ccu) +{ + unsigned long flags; + unsigned int which; + struct kona_clk *kona_clks = ccu->kona_clks; + bool success = true; + + flags = ccu_lock(ccu); + __ccu_write_enable(ccu); + + for (which = 0; which < ccu->clk_num; which++) { + struct kona_clk *bcm_clk = &kona_clks[which]; + + if (!bcm_clk->ccu) + continue; + + success &= __kona_clk_init(bcm_clk); + } + + __ccu_write_disable(ccu); + ccu_unlock(ccu, flags); + return success; +} |