cregit-Linux how code gets into the kernel

Release 4.7 drivers/clk/ingenic/cgu.c

/*
 * Ingenic SoC CGU driver
 *
 * Copyright (c) 2013-2015 Imagination Technologies
 * Author: Paul Burton <paul.burton@imgtec.com>
 *
 * 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; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/delay.h>
#include <linux/math64.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include "cgu.h"


#define MHZ (1000 * 1000)

/**
 * ingenic_cgu_gate_get() - get the value of clock gate register bit
 * @cgu: reference to the CGU whose registers should be read
 * @info: info struct describing the gate bit
 *
 * Retrieves the state of the clock gate bit described by info. The
 * caller must hold cgu->lock.
 *
 * Return: true if the gate bit is set, else false.
 */

static inline bool ingenic_cgu_gate_get(struct ingenic_cgu *cgu, const struct ingenic_cgu_gate_info *info) { return readl(cgu->base + info->reg) & BIT(info->bit); }

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/** * ingenic_cgu_gate_set() - set the value of clock gate register bit * @cgu: reference to the CGU whose registers should be modified * @info: info struct describing the gate bit * @val: non-zero to gate a clock, otherwise zero * * Sets the given gate bit in order to gate or ungate a clock. * * The caller must hold cgu->lock. */
static inline void ingenic_cgu_gate_set(struct ingenic_cgu *cgu, const struct ingenic_cgu_gate_info *info, bool val) { u32 clkgr = readl(cgu->base + info->reg); if (val) clkgr |= BIT(info->bit); else clkgr &= ~BIT(info->bit); writel(clkgr, cgu->base + info->reg); }

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/* * PLL operations */
static unsigned long ingenic_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; const struct ingenic_cgu_pll_info *pll_info; unsigned m, n, od_enc, od; bool bypass, enable; unsigned long flags; u32 ctl; clk_info = &cgu->clock_info[ingenic_clk->idx]; BUG_ON(clk_info->type != CGU_CLK_PLL); pll_info = &clk_info->pll; spin_lock_irqsave(&cgu->lock, flags); ctl = readl(cgu->base + pll_info->reg); spin_unlock_irqrestore(&cgu->lock, flags); m = (ctl >> pll_info->m_shift) & GENMASK(pll_info->m_bits - 1, 0); m += pll_info->m_offset; n = (ctl >> pll_info->n_shift) & GENMASK(pll_info->n_bits - 1, 0); n += pll_info->n_offset; od_enc = ctl >> pll_info->od_shift; od_enc &= GENMASK(pll_info->od_bits - 1, 0); bypass = !!(ctl & BIT(pll_info->bypass_bit)); enable = !!(ctl & BIT(pll_info->enable_bit)); if (bypass) return parent_rate; if (!enable) return 0; for (od = 0; od < pll_info->od_max; od++) { if (pll_info->od_encoding[od] == od_enc) break; } BUG_ON(od == pll_info->od_max); od++; return div_u64((u64)parent_rate * m, n * od); }

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static unsigned long ingenic_pll_calc(const struct ingenic_cgu_clk_info *clk_info, unsigned long rate, unsigned long parent_rate, unsigned *pm, unsigned *pn, unsigned *pod) { const struct ingenic_cgu_pll_info *pll_info; unsigned m, n, od; pll_info = &clk_info->pll; od = 1; /* * The frequency after the input divider must be between 10 and 50 MHz. * The highest divider yields the best resolution. */ n = parent_rate / (10 * MHZ); n = min_t(unsigned, n, 1 << clk_info->pll.n_bits); n = max_t(unsigned, n, pll_info->n_offset); m = (rate / MHZ) * od * n / (parent_rate / MHZ); m = min_t(unsigned, m, 1 << clk_info->pll.m_bits); m = max_t(unsigned, m, pll_info->m_offset); if (pm) *pm = m; if (pn) *pn = n; if (pod) *pod = od; return div_u64((u64)parent_rate * m, n * od); }

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static long ingenic_pll_round_rate(struct clk_hw *hw, unsigned long req_rate, unsigned long *prate) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; clk_info = &cgu->clock_info[ingenic_clk->idx]; BUG_ON(clk_info->type != CGU_CLK_PLL); return ingenic_pll_calc(clk_info, req_rate, *prate, NULL, NULL, NULL); }

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static int ingenic_pll_set_rate(struct clk_hw *hw, unsigned long req_rate, unsigned long parent_rate) { const unsigned timeout = 100; struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; const struct ingenic_cgu_pll_info *pll_info; unsigned long rate, flags; unsigned m, n, od, i; u32 ctl; clk_info = &cgu->clock_info[ingenic_clk->idx]; BUG_ON(clk_info->type != CGU_CLK_PLL); pll_info = &clk_info->pll; rate = ingenic_pll_calc(clk_info, req_rate, parent_rate, &m, &n, &od); if (rate != req_rate) pr_info("ingenic-cgu: request '%s' rate %luHz, actual %luHz\n", clk_info->name, req_rate, rate); spin_lock_irqsave(&cgu->lock, flags); ctl = readl(cgu->base + pll_info->reg); ctl &= ~(GENMASK(pll_info->m_bits - 1, 0) << pll_info->m_shift); ctl |= (m - pll_info->m_offset) << pll_info->m_shift; ctl &= ~(GENMASK(pll_info->n_bits - 1, 0) << pll_info->n_shift); ctl |= (n - pll_info->n_offset) << pll_info->n_shift; ctl &= ~(GENMASK(pll_info->od_bits - 1, 0) << pll_info->od_shift); ctl |= pll_info->od_encoding[od - 1] << pll_info->od_shift; ctl &= ~BIT(pll_info->bypass_bit); ctl |= BIT(pll_info->enable_bit); writel(ctl, cgu->base + pll_info->reg); /* wait for the PLL to stabilise */ for (i = 0; i < timeout; i++) { ctl = readl(cgu->base + pll_info->reg); if (ctl & BIT(pll_info->stable_bit)) break; mdelay(1); } spin_unlock_irqrestore(&cgu->lock, flags); if (i == timeout) return -EBUSY; return 0; }

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static const struct clk_ops ingenic_pll_ops = { .recalc_rate = ingenic_pll_recalc_rate, .round_rate = ingenic_pll_round_rate, .set_rate = ingenic_pll_set_rate, }; /* * Operations for all non-PLL clocks */
static u8 ingenic_clk_get_parent(struct clk_hw *hw) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; u32 reg; u8 i, hw_idx, idx = 0; clk_info = &cgu->clock_info[ingenic_clk->idx]; if (clk_info->type & CGU_CLK_MUX) { reg = readl(cgu->base + clk_info->mux.reg); hw_idx = (reg >> clk_info->mux.shift) & GENMASK(clk_info->mux.bits - 1, 0); /* * Convert the hardware index to the parent index by skipping * over any -1's in the parents array. */ for (i = 0; i < hw_idx; i++) { if (clk_info->parents[i] != -1) idx++; } } return idx; }

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static int ingenic_clk_set_parent(struct clk_hw *hw, u8 idx) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; unsigned long flags; u8 curr_idx, hw_idx, num_poss; u32 reg, mask; clk_info = &cgu->clock_info[ingenic_clk->idx]; if (clk_info->type & CGU_CLK_MUX) { /* * Convert the parent index to the hardware index by adding * 1 for any -1 in the parents array preceding the given * index. That is, we want the index of idx'th entry in * clk_info->parents which does not equal -1. */ hw_idx = curr_idx = 0; num_poss = 1 << clk_info->mux.bits; for (; hw_idx < num_poss; hw_idx++) { if (clk_info->parents[hw_idx] == -1) continue; if (curr_idx == idx) break; curr_idx++; } /* idx should always be a valid parent */ BUG_ON(curr_idx != idx); mask = GENMASK(clk_info->mux.bits - 1, 0); mask <<= clk_info->mux.shift; spin_lock_irqsave(&cgu->lock, flags); /* write the register */ reg = readl(cgu->base + clk_info->mux.reg); reg &= ~mask; reg |= hw_idx << clk_info->mux.shift; writel(reg, cgu->base + clk_info->mux.reg); spin_unlock_irqrestore(&cgu->lock, flags); return 0; } return idx ? -EINVAL : 0; }

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static unsigned long ingenic_clk_recalc_rate(struct clk_hw *hw, unsigned long parent_rate) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; unsigned long rate = parent_rate; u32 div_reg, div; clk_info = &cgu->clock_info[ingenic_clk->idx]; if (clk_info->type & CGU_CLK_DIV) { div_reg = readl(cgu->base + clk_info->div.reg); div = (div_reg >> clk_info->div.shift) & GENMASK(clk_info->div.bits - 1, 0); div += 1; div *= clk_info->div.div; rate /= div; } return rate; }

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static unsigned ingenic_clk_calc_div(const struct ingenic_cgu_clk_info *clk_info, unsigned long parent_rate, unsigned long req_rate) { unsigned div; /* calculate the divide */ div = DIV_ROUND_UP(parent_rate, req_rate); /* and impose hardware constraints */ div = min_t(unsigned, div, 1 << clk_info->div.bits); div = max_t(unsigned, div, 1); /* * If the divider value itself must be divided before being written to * the divider register, we must ensure we don't have any bits set that * would be lost as a result of doing so. */ div /= clk_info->div.div; div *= clk_info->div.div; return div; }

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static long ingenic_clk_round_rate(struct clk_hw *hw, unsigned long req_rate, unsigned long *parent_rate) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; long rate = *parent_rate; clk_info = &cgu->clock_info[ingenic_clk->idx]; if (clk_info->type & CGU_CLK_DIV) rate /= ingenic_clk_calc_div(clk_info, *parent_rate, req_rate); else if (clk_info->type & CGU_CLK_FIXDIV) rate /= clk_info->fixdiv.div; return rate; }

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static int ingenic_clk_set_rate(struct clk_hw *hw, unsigned long req_rate, unsigned long parent_rate) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; const unsigned timeout = 100; unsigned long rate, flags; unsigned div, i; u32 reg, mask; int ret = 0; clk_info = &cgu->clock_info[ingenic_clk->idx]; if (clk_info->type & CGU_CLK_DIV) { div = ingenic_clk_calc_div(clk_info, parent_rate, req_rate); rate = parent_rate / div; if (rate != req_rate) return -EINVAL; spin_lock_irqsave(&cgu->lock, flags); reg = readl(cgu->base + clk_info->div.reg); /* update the divide */ mask = GENMASK(clk_info->div.bits - 1, 0); reg &= ~(mask << clk_info->div.shift); reg |= ((div / clk_info->div.div) - 1) << clk_info->div.shift; /* clear the stop bit */ if (clk_info->div.stop_bit != -1) reg &= ~BIT(clk_info->div.stop_bit); /* set the change enable bit */ if (clk_info->div.ce_bit != -1) reg |= BIT(clk_info->div.ce_bit); /* update the hardware */ writel(reg, cgu->base + clk_info->div.reg); /* wait for the change to take effect */ if (clk_info->div.busy_bit != -1) { for (i = 0; i < timeout; i++) { reg = readl(cgu->base + clk_info->div.reg); if (!(reg & BIT(clk_info->div.busy_bit))) break; mdelay(1); } if (i == timeout) ret = -EBUSY; } spin_unlock_irqrestore(&cgu->lock, flags); return ret; } return -EINVAL; }

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static int ingenic_clk_enable(struct clk_hw *hw) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; unsigned long flags; clk_info = &cgu->clock_info[ingenic_clk->idx]; if (clk_info->type & CGU_CLK_GATE) { /* ungate the clock */ spin_lock_irqsave(&cgu->lock, flags); ingenic_cgu_gate_set(cgu, &clk_info->gate, false); spin_unlock_irqrestore(&cgu->lock, flags); } return 0; }

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static void ingenic_clk_disable(struct clk_hw *hw) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; unsigned long flags; clk_info = &cgu->clock_info[ingenic_clk->idx]; if (clk_info->type & CGU_CLK_GATE) { /* gate the clock */ spin_lock_irqsave(&cgu->lock, flags); ingenic_cgu_gate_set(cgu, &clk_info->gate, true); spin_unlock_irqrestore(&cgu->lock, flags); } }

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static int ingenic_clk_is_enabled(struct clk_hw *hw) { struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw); struct ingenic_cgu *cgu = ingenic_clk->cgu; const struct ingenic_cgu_clk_info *clk_info; unsigned long flags; int enabled = 1; clk_info = &cgu->clock_info[ingenic_clk->idx]; if (clk_info->type & CGU_CLK_GATE) { spin_lock_irqsave(&cgu->lock, flags); enabled = !ingenic_cgu_gate_get(cgu, &clk_info->gate); spin_unlock_irqrestore(&cgu->lock, flags); } return enabled; }

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static const struct clk_ops ingenic_clk_ops = { .get_parent = ingenic_clk_get_parent, .set_parent = ingenic_clk_set_parent, .recalc_rate = ingenic_clk_recalc_rate, .round_rate = ingenic_clk_round_rate, .set_rate = ingenic_clk_set_rate, .enable = ingenic_clk_enable, .disable = ingenic_clk_disable, .is_enabled = ingenic_clk_is_enabled, }; /* * Setup functions. */
static int ingenic_register_clock(struct ingenic_cgu *cgu, unsigned idx) { const struct ingenic_cgu_clk_info *clk_info = &cgu->clock_info[idx]; struct clk_init_data clk_init; struct ingenic_clk *ingenic_clk = NULL; struct clk *clk, *parent; const char *parent_names[4]; unsigned caps, i, num_possible; int err = -EINVAL; BUILD_BUG_ON(ARRAY_SIZE(clk_info->parents) > ARRAY_SIZE(parent_names)); if (clk_info->type == CGU_CLK_EXT) { clk = of_clk_get_by_name(cgu->np, clk_info->name); if (IS_ERR(clk)) { pr_err("%s: no external clock '%s' provided\n", __func__, clk_info->name); err = -ENODEV; goto out; } err = clk_register_clkdev(clk, clk_info->name, NULL); if (err) { clk_put(clk); goto out; } cgu->clocks.clks[idx] = clk; return 0; } if (!clk_info->type) { pr_err("%s: no clock type specified for '%s'\n", __func__, clk_info->name); goto out; } ingenic_clk = kzalloc(sizeof(*ingenic_clk), GFP_KERNEL); if (!ingenic_clk) { err = -ENOMEM; goto out; } ingenic_clk->hw.init = &clk_init; ingenic_clk->cgu = cgu; ingenic_clk->idx = idx; clk_init.name = clk_info->name; clk_init.flags = 0; clk_init.parent_names = parent_names; caps = clk_info->type; if (caps & (CGU_CLK_MUX | CGU_CLK_CUSTOM)) { clk_init.num_parents = 0; if (caps & CGU_CLK_MUX) num_possible = 1 << clk_info->mux.bits; else num_possible = ARRAY_SIZE(clk_info->parents); for (i = 0; i < num_possible; i++) { if (clk_info->parents[i] == -1) continue; parent = cgu->clocks.clks[clk_info->parents[i]]; parent_names[clk_init.num_parents] = __clk_get_name(parent); clk_init.num_parents++; } BUG_ON(!clk_init.num_parents); BUG_ON(clk_init.num_parents > ARRAY_SIZE(parent_names)); } else { BUG_ON(clk_info->parents[0] == -1); clk_init.num_parents = 1; parent = cgu->clocks.clks[clk_info->parents[0]]; parent_names[0] = __clk_get_name(parent); } if (caps & CGU_CLK_CUSTOM) { clk_init.ops = clk_info->custom.clk_ops; caps &= ~CGU_CLK_CUSTOM; if (caps) { pr_err("%s: custom clock may not be combined with type 0x%x\n", __func__, caps); goto out; } } else if (caps & CGU_CLK_PLL) { clk_init.ops = &ingenic_pll_ops; caps &= ~CGU_CLK_PLL; if (caps) { pr_err("%s: PLL may not be combined with type 0x%x\n", __func__, caps); goto out; } } else { clk_init.ops = &ingenic_clk_ops; } /* nothing to do for gates or fixed dividers */ caps &= ~(CGU_CLK_GATE | CGU_CLK_FIXDIV); if (caps & CGU_CLK_MUX) { if (!(caps & CGU_CLK_MUX_GLITCHFREE)) clk_init.flags |= CLK_SET_PARENT_GATE; caps &= ~(CGU_CLK_MUX | CGU_CLK_MUX_GLITCHFREE); } if (caps & CGU_CLK_DIV) { caps &= ~CGU_CLK_DIV; } else { /* pass rate changes to the parent clock */ clk_init.flags |= CLK_SET_RATE_PARENT; } if (caps) { pr_err("%s: unknown clock type 0x%x\n", __func__, caps); goto out; } clk = clk_register(NULL, &ingenic_clk->hw); if (IS_ERR(clk)) { pr_err("%s: failed to register clock '%s'\n", __func__, clk_info->name); err = PTR_ERR(clk); goto out; } err = clk_register_clkdev(clk, clk_info->name, NULL); if (err) goto out; cgu->clocks.clks[idx] = clk; out: if (err) kfree(ingenic_clk); return err; }

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struct ingenic_cgu * ingenic_cgu_new(const struct ingenic_cgu_clk_info *clock_info, unsigned num_clocks, struct device_node *np) { struct ingenic_cgu *cgu; cgu = kzalloc(sizeof(*cgu), GFP_KERNEL); if (!cgu) goto err_out; cgu->base = of_iomap(np, 0); if (!cgu->base) { pr_err("%s: failed to map CGU registers\n", __func__); goto err_out_free; } cgu->np = np; cgu->clock_info = clock_info; cgu->clocks.clk_num = num_clocks; spin_lock_init(&cgu->lock); return cgu; err_out_free: kfree(cgu); err_out: return NULL; }

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int ingenic_cgu_register_clocks(struct ingenic_cgu *cgu) { unsigned i; int err; cgu->clocks.clks = kcalloc(cgu->clocks.clk_num, sizeof(struct clk *), GFP_KERNEL); if (!cgu->clocks.clks) { err = -ENOMEM; goto err_out; } for (i = 0; i < cgu->clocks.clk_num; i++) { err = ingenic_register_clock(cgu, i); if (err) goto err_out_unregister; } err = of_clk_add_provider(cgu->np, of_clk_src_onecell_get, &cgu->clocks); if (err) goto err_out_unregister; return 0; err_out_unregister: for (i = 0; i < cgu->clocks.clk_num; i++) { if (!cgu->clocks.clks[i]) continue; if (cgu->clock_info[i].type & CGU_CLK_EXT) clk_put(cgu->clocks.clks[i]); else clk_unregister(cgu->clocks.clks[i]); } kfree(cgu->clocks.clks); err_out: return err; }

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