/* * linux/arch/arm/mach-omap2/clock.c * * Copyright (C) 2005-2008 Texas Instruments, Inc. * Copyright (C) 2004-2008 Nokia Corporation * * Contacts: * Richard Woodruff * Paul Walmsley * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #undef DEBUG #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "sdrc.h" #include "clock.h" #include "prm.h" #include "prm-regbits-24xx.h" #include "cm.h" #include "cm-regbits-24xx.h" #include "cm-regbits-34xx.h" /* DPLL rate rounding: minimum DPLL multiplier, divider values */ #define DPLL_MIN_MULTIPLIER 1 #define DPLL_MIN_DIVIDER 1 /* Possible error results from _dpll_test_mult */ #define DPLL_MULT_UNDERFLOW -1 /* * Scale factor to mitigate roundoff errors in DPLL rate rounding. * The higher the scale factor, the greater the risk of arithmetic overflow, * but the closer the rounded rate to the target rate. DPLL_SCALE_FACTOR * must be a power of DPLL_SCALE_BASE. */ #define DPLL_SCALE_FACTOR 64 #define DPLL_SCALE_BASE 2 #define DPLL_ROUNDING_VAL ((DPLL_SCALE_BASE / 2) * \ (DPLL_SCALE_FACTOR / DPLL_SCALE_BASE)) /* DPLL valid Fint frequency band limits - from 34xx TRM Section 4.7.6.2 */ #define DPLL_FINT_BAND1_MIN 750000 #define DPLL_FINT_BAND1_MAX 2100000 #define DPLL_FINT_BAND2_MIN 7500000 #define DPLL_FINT_BAND2_MAX 21000000 /* _dpll_test_fint() return codes */ #define DPLL_FINT_UNDERFLOW -1 #define DPLL_FINT_INVALID -2 u8 cpu_mask; /*------------------------------------------------------------------------- * OMAP2/3/4 specific clock functions *-------------------------------------------------------------------------*/ void omap2_init_dpll_parent(struct clk *clk) { u32 v; struct dpll_data *dd; dd = clk->dpll_data; if (!dd) return; /* Return bypass rate if DPLL is bypassed */ v = __raw_readl(dd->control_reg); v &= dd->enable_mask; v >>= __ffs(dd->enable_mask); /* Reparent in case the dpll is in bypass */ if (cpu_is_omap24xx()) { if (v == OMAP2XXX_EN_DPLL_LPBYPASS || v == OMAP2XXX_EN_DPLL_FRBYPASS) clk_reparent(clk, dd->clk_bypass); } else if (cpu_is_omap34xx()) { if (v == OMAP3XXX_EN_DPLL_LPBYPASS || v == OMAP3XXX_EN_DPLL_FRBYPASS) clk_reparent(clk, dd->clk_bypass); } else if (cpu_is_omap44xx()) { if (v == OMAP4XXX_EN_DPLL_LPBYPASS || v == OMAP4XXX_EN_DPLL_FRBYPASS || v == OMAP4XXX_EN_DPLL_MNBYPASS) clk_reparent(clk, dd->clk_bypass); } return; } /** * _omap2xxx_clk_commit - commit clock parent/rate changes in hardware * @clk: struct clk * * * If @clk has the DELAYED_APP flag set, meaning that parent/rate changes * don't take effect until the VALID_CONFIG bit is written, write the * VALID_CONFIG bit and wait for the write to complete. No return value. */ static void _omap2xxx_clk_commit(struct clk *clk) { if (!cpu_is_omap24xx()) return; if (!(clk->flags & DELAYED_APP)) return; prm_write_mod_reg(OMAP24XX_VALID_CONFIG, OMAP24XX_GR_MOD, OMAP2_PRCM_CLKCFG_CTRL_OFFSET); /* OCP barrier */ prm_read_mod_reg(OMAP24XX_GR_MOD, OMAP2_PRCM_CLKCFG_CTRL_OFFSET); } /* * _dpll_test_fint - test whether an Fint value is valid for the DPLL * @clk: DPLL struct clk to test * @n: divider value (N) to test * * Tests whether a particular divider @n will result in a valid DPLL * internal clock frequency Fint. See the 34xx TRM 4.7.6.2 "DPLL Jitter * Correction". Returns 0 if OK, -1 if the enclosing loop can terminate * (assuming that it is counting N upwards), or -2 if the enclosing loop * should skip to the next iteration (again assuming N is increasing). */ static int _dpll_test_fint(struct clk *clk, u8 n) { struct dpll_data *dd; long fint; int ret = 0; dd = clk->dpll_data; /* DPLL divider must result in a valid jitter correction val */ fint = clk->parent->rate / (n + 1); if (fint < DPLL_FINT_BAND1_MIN) { pr_debug("rejecting n=%d due to Fint failure, " "lowering max_divider\n", n); dd->max_divider = n; ret = DPLL_FINT_UNDERFLOW; } else if (fint > DPLL_FINT_BAND1_MAX && fint < DPLL_FINT_BAND2_MIN) { pr_debug("rejecting n=%d due to Fint failure\n", n); ret = DPLL_FINT_INVALID; } else if (fint > DPLL_FINT_BAND2_MAX) { pr_debug("rejecting n=%d due to Fint failure, " "boosting min_divider\n", n); dd->min_divider = n; ret = DPLL_FINT_INVALID; } return ret; } /** * omap2_init_clk_clkdm - look up a clockdomain name, store pointer in clk * @clk: OMAP clock struct ptr to use * * Convert a clockdomain name stored in a struct clk 'clk' into a * clockdomain pointer, and save it into the struct clk. Intended to be * called during clk_register(). No return value. */ void omap2_init_clk_clkdm(struct clk *clk) { struct clockdomain *clkdm; if (!clk->clkdm_name) return; clkdm = clkdm_lookup(clk->clkdm_name); if (clkdm) { pr_debug("clock: associated clk %s to clkdm %s\n", clk->name, clk->clkdm_name); clk->clkdm = clkdm; } else { pr_debug("clock: could not associate clk %s to " "clkdm %s\n", clk->name, clk->clkdm_name); } } /** * omap2_init_clksel_parent - set a clksel clk's parent field from the hardware * @clk: OMAP clock struct ptr to use * * Given a pointer to a source-selectable struct clk, read the hardware * register and determine what its parent is currently set to. Update the * clk->parent field with the appropriate clk ptr. */ void omap2_init_clksel_parent(struct clk *clk) { const struct clksel *clks; const struct clksel_rate *clkr; u32 r, found = 0; if (!clk->clksel) return; r = __raw_readl(clk->clksel_reg) & clk->clksel_mask; r >>= __ffs(clk->clksel_mask); for (clks = clk->clksel; clks->parent && !found; clks++) { for (clkr = clks->rates; clkr->div && !found; clkr++) { if ((clkr->flags & cpu_mask) && (clkr->val == r)) { if (clk->parent != clks->parent) { pr_debug("clock: inited %s parent " "to %s (was %s)\n", clk->name, clks->parent->name, ((clk->parent) ? clk->parent->name : "NULL")); clk_reparent(clk, clks->parent); }; found = 1; } } } if (!found) printk(KERN_ERR "clock: init parent: could not find " "regval %0x for clock %s\n", r, clk->name); return; } /** * omap2_get_dpll_rate - returns the current DPLL CLKOUT rate * @clk: struct clk * of a DPLL * * DPLLs can be locked or bypassed - basically, enabled or disabled. * When locked, the DPLL output depends on the M and N values. When * bypassed, on OMAP2xxx, the output rate is either the 32KiHz clock * or sys_clk. Bypass rates on OMAP3 depend on the DPLL: DPLLs 1 and * 2 are bypassed with dpll1_fclk and dpll2_fclk respectively * (generated by DPLL3), while DPLL 3, 4, and 5 bypass rates are sys_clk. * Returns the current DPLL CLKOUT rate (*not* CLKOUTX2) if the DPLL is * locked, or the appropriate bypass rate if the DPLL is bypassed, or 0 * if the clock @clk is not a DPLL. */ u32 omap2_get_dpll_rate(struct clk *clk) { long long dpll_clk; u32 dpll_mult, dpll_div, v; struct dpll_data *dd; dd = clk->dpll_data; if (!dd) return 0; /* Return bypass rate if DPLL is bypassed */ v = __raw_readl(dd->control_reg); v &= dd->enable_mask; v >>= __ffs(dd->enable_mask); if (cpu_is_omap24xx()) { if (v == OMAP2XXX_EN_DPLL_LPBYPASS || v == OMAP2XXX_EN_DPLL_FRBYPASS) return dd->clk_bypass->rate; } else if (cpu_is_omap34xx()) { if (v == OMAP3XXX_EN_DPLL_LPBYPASS || v == OMAP3XXX_EN_DPLL_FRBYPASS) return dd->clk_bypass->rate; } else if (cpu_is_omap44xx()) { if (v == OMAP4XXX_EN_DPLL_LPBYPASS || v == OMAP4XXX_EN_DPLL_FRBYPASS || v == OMAP4XXX_EN_DPLL_MNBYPASS) return dd->clk_bypass->rate; } v = __raw_readl(dd->mult_div1_reg); dpll_mult = v & dd->mult_mask; dpll_mult >>= __ffs(dd->mult_mask); dpll_div = v & dd->div1_mask; dpll_div >>= __ffs(dd->div1_mask); dpll_clk = (long long)dd->clk_ref->rate * dpll_mult; do_div(dpll_clk, dpll_div + 1); return dpll_clk; } /** * omap2_clk_dflt_find_companion - find companion clock to @clk * @clk: struct clk * to find the companion clock of * @other_reg: void __iomem ** to return the companion clock CM_*CLKEN va in * @other_bit: u8 ** to return the companion clock bit shift in * * Note: We don't need special code here for INVERT_ENABLE for the * time being since INVERT_ENABLE only applies to clocks enabled by * CM_CLKEN_PLL * * Convert CM_ICLKEN* <-> CM_FCLKEN*. This conversion assumes it's * just a matter of XORing the bits. * * Some clocks don't have companion clocks. For example, modules with * only an interface clock (such as MAILBOXES) don't have a companion * clock. Right now, this code relies on the hardware exporting a bit * in the correct companion register that indicates that the * nonexistent 'companion clock' is active. Future patches will * associate this type of code with per-module data structures to * avoid this issue, and remove the casts. No return value. */ void omap2_clk_dflt_find_companion(struct clk *clk, void __iomem **other_reg, u8 *other_bit) { u32 r; /* * Convert CM_ICLKEN* <-> CM_FCLKEN*. This conversion assumes * it's just a matter of XORing the bits. */ r = ((__force u32)clk->enable_reg ^ (CM_FCLKEN ^ CM_ICLKEN)); *other_reg = (__force void __iomem *)r; *other_bit = clk->enable_bit; } /** * omap2_clk_dflt_find_idlest - find CM_IDLEST reg va, bit shift for @clk * @clk: struct clk * to find IDLEST info for * @idlest_reg: void __iomem ** to return the CM_IDLEST va in * @idlest_bit: u8 ** to return the CM_IDLEST bit shift in * * Return the CM_IDLEST register address and bit shift corresponding * to the module that "owns" this clock. This default code assumes * that the CM_IDLEST bit shift is the CM_*CLKEN bit shift, and that * the IDLEST register address ID corresponds to the CM_*CLKEN * register address ID (e.g., that CM_FCLKEN2 corresponds to * CM_IDLEST2). This is not true for all modules. No return value. */ void omap2_clk_dflt_find_idlest(struct clk *clk, void __iomem **idlest_reg, u8 *idlest_bit) { u32 r; r = (((__force u32)clk->enable_reg & ~0xf0) | 0x20); *idlest_reg = (__force void __iomem *)r; *idlest_bit = clk->enable_bit; } /** * omap2_module_wait_ready - wait for an OMAP module to leave IDLE * @clk: struct clk * belonging to the module * * If the necessary clocks for the OMAP hardware IP block that * corresponds to clock @clk are enabled, then wait for the module to * indicate readiness (i.e., to leave IDLE). This code does not * belong in the clock code and will be moved in the medium term to * module-dependent code. No return value. */ static void omap2_module_wait_ready(struct clk *clk) { void __iomem *companion_reg, *idlest_reg; u8 other_bit, idlest_bit; /* Not all modules have multiple clocks that their IDLEST depends on */ if (clk->ops->find_companion) { clk->ops->find_companion(clk, &companion_reg, &other_bit); if (!(__raw_readl(companion_reg) & (1 << other_bit))) return; } clk->ops->find_idlest(clk, &idlest_reg, &idlest_bit); omap2_cm_wait_idlest(idlest_reg, (1 << idlest_bit), clk->name); } int omap2_dflt_clk_enable(struct clk *clk) { u32 v; if (unlikely(clk->enable_reg == NULL)) { pr_err("clock.c: Enable for %s without enable code\n", clk->name); return 0; /* REVISIT: -EINVAL */ } v = __raw_readl(clk->enable_reg); if (clk->flags & INVERT_ENABLE) v &= ~(1 << clk->enable_bit); else v |= (1 << clk->enable_bit); __raw_writel(v, clk->enable_reg); v = __raw_readl(clk->enable_reg); /* OCP barrier */ if (clk->ops->find_idlest) omap2_module_wait_ready(clk); return 0; } void omap2_dflt_clk_disable(struct clk *clk) { u32 v; if (!clk->enable_reg) { /* * 'Independent' here refers to a clock which is not * controlled by its parent. */ printk(KERN_ERR "clock: clk_disable called on independent " "clock %s which has no enable_reg\n", clk->name); return; } v = __raw_readl(clk->enable_reg); if (clk->flags & INVERT_ENABLE) v |= (1 << clk->enable_bit); else v &= ~(1 << clk->enable_bit); __raw_writel(v, clk->enable_reg); /* No OCP barrier needed here since it is a disable operation */ } const struct clkops clkops_omap2_dflt_wait = { .enable = omap2_dflt_clk_enable, .disable = omap2_dflt_clk_disable, .find_companion = omap2_clk_dflt_find_companion, .find_idlest = omap2_clk_dflt_find_idlest, }; const struct clkops clkops_omap2_dflt = { .enable = omap2_dflt_clk_enable, .disable = omap2_dflt_clk_disable, }; /* Enables clock without considering parent dependencies or use count * REVISIT: Maybe change this to use clk->enable like on omap1? */ static int _omap2_clk_enable(struct clk *clk) { return clk->ops->enable(clk); } /* Disables clock without considering parent dependencies or use count */ static void _omap2_clk_disable(struct clk *clk) { clk->ops->disable(clk); } void omap2_clk_disable(struct clk *clk) { if (clk->usecount > 0 && !(--clk->usecount)) { _omap2_clk_disable(clk); if (clk->parent) omap2_clk_disable(clk->parent); if (clk->clkdm) omap2_clkdm_clk_disable(clk->clkdm, clk); } } int omap2_clk_enable(struct clk *clk) { int ret = 0; if (clk->usecount++ == 0) { if (clk->clkdm) omap2_clkdm_clk_enable(clk->clkdm, clk); if (clk->parent) { ret = omap2_clk_enable(clk->parent); if (ret) goto err; } ret = _omap2_clk_enable(clk); if (ret) { if (clk->parent) omap2_clk_disable(clk->parent); goto err; } } return ret; err: if (clk->clkdm) omap2_clkdm_clk_disable(clk->clkdm, clk); clk->usecount--; return ret; } /* * Used for clocks that are part of CLKSEL_xyz governed clocks. * REVISIT: Maybe change to use clk->enable() functions like on omap1? */ unsigned long omap2_clksel_recalc(struct clk *clk) { unsigned long rate; u32 div = 0; pr_debug("clock: recalc'ing clksel clk %s\n", clk->name); div = omap2_clksel_get_divisor(clk); if (div == 0) return clk->rate; rate = clk->parent->rate / div; pr_debug("clock: new clock rate is %ld (div %d)\n", rate, div); return rate; } /** * omap2_get_clksel_by_parent - return clksel struct for a given clk & parent * @clk: OMAP struct clk ptr to inspect * @src_clk: OMAP struct clk ptr of the parent clk to search for * * Scan the struct clksel array associated with the clock to find * the element associated with the supplied parent clock address. * Returns a pointer to the struct clksel on success or NULL on error. */ static const struct clksel *omap2_get_clksel_by_parent(struct clk *clk, struct clk *src_clk) { const struct clksel *clks; if (!clk->clksel) return NULL; for (clks = clk->clksel; clks->parent; clks++) { if (clks->parent == src_clk) break; /* Found the requested parent */ } if (!clks->parent) { printk(KERN_ERR "clock: Could not find parent clock %s in " "clksel array of clock %s\n", src_clk->name, clk->name); return NULL; } return clks; } /** * omap2_clksel_round_rate_div - find divisor for the given clock and rate * @clk: OMAP struct clk to use * @target_rate: desired clock rate * @new_div: ptr to where we should store the divisor * * Finds 'best' divider value in an array based on the source and target * rates. The divider array must be sorted with smallest divider first. * Note that this will not work for clocks which are part of CONFIG_PARTICIPANT, * they are only settable as part of virtual_prcm set. * * Returns the rounded clock rate or returns 0xffffffff on error. */ u32 omap2_clksel_round_rate_div(struct clk *clk, unsigned long target_rate, u32 *new_div) { unsigned long test_rate; const struct clksel *clks; const struct clksel_rate *clkr; u32 last_div = 0; pr_debug("clock: clksel_round_rate_div: %s target_rate %ld\n", clk->name, target_rate); *new_div = 1; clks = omap2_get_clksel_by_parent(clk, clk->parent); if (!clks) return ~0; for (clkr = clks->rates; clkr->div; clkr++) { if (!(clkr->flags & cpu_mask)) continue; /* Sanity check */ if (clkr->div <= last_div) pr_err("clock: clksel_rate table not sorted " "for clock %s", clk->name); last_div = clkr->div; test_rate = clk->parent->rate / clkr->div; if (test_rate <= target_rate) break; /* found it */ } if (!clkr->div) { pr_err("clock: Could not find divisor for target " "rate %ld for clock %s parent %s\n", target_rate, clk->name, clk->parent->name); return ~0; } *new_div = clkr->div; pr_debug("clock: new_div = %d, new_rate = %ld\n", *new_div, (clk->parent->rate / clkr->div)); return (clk->parent->rate / clkr->div); } /** * omap2_clksel_round_rate - find rounded rate for the given clock and rate * @clk: OMAP struct clk to use * @target_rate: desired clock rate * * Compatibility wrapper for OMAP clock framework * Finds best target rate based on the source clock and possible dividers. * rates. The divider array must be sorted with smallest divider first. * Note that this will not work for clocks which are part of CONFIG_PARTICIPANT, * they are only settable as part of virtual_prcm set. * * Returns the rounded clock rate or returns 0xffffffff on error. */ long omap2_clksel_round_rate(struct clk *clk, unsigned long target_rate) { u32 new_div; return omap2_clksel_round_rate_div(clk, target_rate, &new_div); } /* Given a clock and a rate apply a clock specific rounding function */ long omap2_clk_round_rate(struct clk *clk, unsigned long rate) { if (clk->round_rate) return clk->round_rate(clk, rate); if (clk->flags & RATE_FIXED) printk(KERN_ERR "clock: generic omap2_clk_round_rate called " "on fixed-rate clock %s\n", clk->name); return clk->rate; } /** * omap2_clksel_to_divisor() - turn clksel field value into integer divider * @clk: OMAP struct clk to use * @field_val: register field value to find * * Given a struct clk of a rate-selectable clksel clock, and a register field * value to search for, find the corresponding clock divisor. The register * field value should be pre-masked and shifted down so the LSB is at bit 0 * before calling. Returns 0 on error */ u32 omap2_clksel_to_divisor(struct clk *clk, u32 field_val) { const struct clksel *clks; const struct clksel_rate *clkr; clks = omap2_get_clksel_by_parent(clk, clk->parent); if (!clks) return 0; for (clkr = clks->rates; clkr->div; clkr++) { if ((clkr->flags & cpu_mask) && (clkr->val == field_val)) break; } if (!clkr->div) { printk(KERN_ERR "clock: Could not find fieldval %d for " "clock %s parent %s\n", field_val, clk->name, clk->parent->name); return 0; } return clkr->div; } /** * omap2_divisor_to_clksel() - turn clksel integer divisor into a field value * @clk: OMAP struct clk to use * @div: integer divisor to search for * * Given a struct clk of a rate-selectable clksel clock, and a clock divisor, * find the corresponding register field value. The return register value is * the value before left-shifting. Returns ~0 on error */ u32 omap2_divisor_to_clksel(struct clk *clk, u32 div) { const struct clksel *clks; const struct clksel_rate *clkr; /* should never happen */ WARN_ON(div == 0); clks = omap2_get_clksel_by_parent(clk, clk->parent); if (!clks) return ~0; for (clkr = clks->rates; clkr->div; clkr++) { if ((clkr->flags & cpu_mask) && (clkr->div == div)) break; } if (!clkr->div) { printk(KERN_ERR "clock: Could not find divisor %d for " "clock %s parent %s\n", div, clk->name, clk->parent->name); return ~0; } return clkr->val; } /** * omap2_clksel_get_divisor - get current divider applied to parent clock. * @clk: OMAP struct clk to use. * * Returns the integer divisor upon success or 0 on error. */ u32 omap2_clksel_get_divisor(struct clk *clk) { u32 v; if (!clk->clksel_mask) return 0; v = __raw_readl(clk->clksel_reg) & clk->clksel_mask; v >>= __ffs(clk->clksel_mask); return omap2_clksel_to_divisor(clk, v); } int omap2_clksel_set_rate(struct clk *clk, unsigned long rate) { u32 v, field_val, validrate, new_div = 0; if (!clk->clksel_mask) return -EINVAL; validrate = omap2_clksel_round_rate_div(clk, rate, &new_div); if (validrate != rate) return -EINVAL; field_val = omap2_divisor_to_clksel(clk, new_div); if (field_val == ~0) return -EINVAL; v = __raw_readl(clk->clksel_reg); v &= ~clk->clksel_mask; v |= field_val << __ffs(clk->clksel_mask); __raw_writel(v, clk->clksel_reg); v = __raw_readl(clk->clksel_reg); /* OCP barrier */ clk->rate = clk->parent->rate / new_div; _omap2xxx_clk_commit(clk); return 0; } /* Set the clock rate for a clock source */ int omap2_clk_set_rate(struct clk *clk, unsigned long rate) { int ret = -EINVAL; pr_debug("clock: set_rate for clock %s to rate %ld\n", clk->name, rate); /* CONFIG_PARTICIPANT clocks are changed only in sets via the rate table mechanism, driven by mpu_speed */ if (clk->flags & CONFIG_PARTICIPANT) return -EINVAL; /* dpll_ck, core_ck, virt_prcm_set; plus all clksel clocks */ if (clk->set_rate) ret = clk->set_rate(clk, rate); return ret; } /* * Converts encoded control register address into a full address * On error, the return value (parent_div) will be 0. */ static u32 _omap2_clksel_get_src_field(struct clk *src_clk, struct clk *clk, u32 *field_val) { const struct clksel *clks; const struct clksel_rate *clkr; clks = omap2_get_clksel_by_parent(clk, src_clk); if (!clks) return 0; for (clkr = clks->rates; clkr->div; clkr++) { if (clkr->flags & cpu_mask && clkr->flags & DEFAULT_RATE) break; /* Found the default rate for this platform */ } if (!clkr->div) { printk(KERN_ERR "clock: Could not find default rate for " "clock %s parent %s\n", clk->name, src_clk->parent->name); return 0; } /* Should never happen. Add a clksel mask to the struct clk. */ WARN_ON(clk->clksel_mask == 0); *field_val = clkr->val; return clkr->div; } int omap2_clk_set_parent(struct clk *clk, struct clk *new_parent) { u32 field_val, v, parent_div; if (clk->flags & CONFIG_PARTICIPANT) return -EINVAL; if (!clk->clksel) return -EINVAL; parent_div = _omap2_clksel_get_src_field(new_parent, clk, &field_val); if (!parent_div) return -EINVAL; /* Set new source value (previous dividers if any in effect) */ v = __raw_readl(clk->clksel_reg); v &= ~clk->clksel_mask; v |= field_val << __ffs(clk->clksel_mask); __raw_writel(v, clk->clksel_reg); v = __raw_readl(clk->clksel_reg); /* OCP barrier */ _omap2xxx_clk_commit(clk); clk_reparent(clk, new_parent); /* CLKSEL clocks follow their parents' rates, divided by a divisor */ clk->rate = new_parent->rate; if (parent_div > 0) clk->rate /= parent_div; pr_debug("clock: set parent of %s to %s (new rate %ld)\n", clk->name, clk->parent->name, clk->rate); return 0; } /* DPLL rate rounding code */ /** * omap2_dpll_set_rate_tolerance: set the error tolerance during rate rounding * @clk: struct clk * of the DPLL * @tolerance: maximum rate error tolerance * * Set the maximum DPLL rate error tolerance for the rate rounding * algorithm. The rate tolerance is an attempt to balance DPLL power * saving (the least divider value "n") vs. rate fidelity (the least * difference between the desired DPLL target rate and the rounded * rate out of the algorithm). So, increasing the tolerance is likely * to decrease DPLL power consumption and increase DPLL rate error. * Returns -EINVAL if provided a null clock ptr or a clk that is not a * DPLL; or 0 upon success. */ int omap2_dpll_set_rate_tolerance(struct clk *clk, unsigned int tolerance) { if (!clk || !clk->dpll_data) return -EINVAL; clk->dpll_data->rate_tolerance = tolerance; return 0; } static unsigned long _dpll_compute_new_rate(unsigned long parent_rate, unsigned int m, unsigned int n) { unsigned long long num; num = (unsigned long long)parent_rate * m; do_div(num, n); return num; } /* * _dpll_test_mult - test a DPLL multiplier value * @m: pointer to the DPLL m (multiplier) value under test * @n: current DPLL n (divider) value under test * @new_rate: pointer to storage for the resulting rounded rate * @target_rate: the desired DPLL rate * @parent_rate: the DPLL's parent clock rate * * This code tests a DPLL multiplier value, ensuring that the * resulting rate will not be higher than the target_rate, and that * the multiplier value itself is valid for the DPLL. Initially, the * integer pointed to by the m argument should be prescaled by * multiplying by DPLL_SCALE_FACTOR. The code will replace this with * a non-scaled m upon return. This non-scaled m will result in a * new_rate as close as possible to target_rate (but not greater than * target_rate) given the current (parent_rate, n, prescaled m) * triple. Returns DPLL_MULT_UNDERFLOW in the event that the * non-scaled m attempted to underflow, which can allow the calling * function to bail out early; or 0 upon success. */ static int _dpll_test_mult(int *m, int n, unsigned long *new_rate, unsigned long target_rate, unsigned long parent_rate) { int r = 0, carry = 0; /* Unscale m and round if necessary */ if (*m % DPLL_SCALE_FACTOR >= DPLL_ROUNDING_VAL) carry = 1; *m = (*m / DPLL_SCALE_FACTOR) + carry; /* * The new rate must be <= the target rate to avoid programming * a rate that is impossible for the hardware to handle */ *new_rate = _dpll_compute_new_rate(parent_rate, *m, n); if (*new_rate > target_rate) { (*m)--; *new_rate = 0; } /* Guard against m underflow */ if (*m < DPLL_MIN_MULTIPLIER) { *m = DPLL_MIN_MULTIPLIER; *new_rate = 0; r = DPLL_MULT_UNDERFLOW; } if (*new_rate == 0) *new_rate = _dpll_compute_new_rate(parent_rate, *m, n); return r; } /** * omap2_dpll_round_rate - round a target rate for an OMAP DPLL * @clk: struct clk * for a DPLL * @target_rate: desired DPLL clock rate * * Given a DPLL, a desired target rate, and a rate tolerance, round * the target rate to a possible, programmable rate for this DPLL. * Rate tolerance is assumed to be set by the caller before this * function is called. Attempts to select the minimum possible n * within the tolerance to reduce power consumption. Stores the * computed (m, n) in the DPLL's dpll_data structure so set_rate() * will not need to call this (expensive) function again. Returns ~0 * if the target rate cannot be rounded, either because the rate is * too low or because the rate tolerance is set too tightly; or the * rounded rate upon success. */ long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate) { int m, n, r, e, scaled_max_m; unsigned long scaled_rt_rp, new_rate; int min_e = -1, min_e_m = -1, min_e_n = -1; struct dpll_data *dd; if (!clk || !clk->dpll_data) return ~0; dd = clk->dpll_data; pr_debug("clock: starting DPLL round_rate for clock %s, target rate " "%ld\n", clk->name, target_rate); scaled_rt_rp = target_rate / (dd->clk_ref->rate / DPLL_SCALE_FACTOR); scaled_max_m = dd->max_multiplier * DPLL_SCALE_FACTOR; dd->last_rounded_rate = 0; for (n = dd->min_divider; n <= dd->max_divider; n++) { /* Is the (input clk, divider) pair valid for the DPLL? */ r = _dpll_test_fint(clk, n); if (r == DPLL_FINT_UNDERFLOW) break; else if (r == DPLL_FINT_INVALID) continue; /* Compute the scaled DPLL multiplier, based on the divider */ m = scaled_rt_rp * n; /* * Since we're counting n up, a m overflow means we * can bail out completely (since as n increases in * the next iteration, there's no way that m can * increase beyond the current m) */ if (m > scaled_max_m) break; r = _dpll_test_mult(&m, n, &new_rate, target_rate, dd->clk_ref->rate); /* m can't be set low enough for this n - try with a larger n */ if (r == DPLL_MULT_UNDERFLOW) continue; e = target_rate - new_rate; pr_debug("clock: n = %d: m = %d: rate error is %d " "(new_rate = %ld)\n", n, m, e, new_rate); if (min_e == -1 || min_e >= (int)(abs(e) - dd->rate_tolerance)) { min_e = e; min_e_m = m; min_e_n = n; pr_debug("clock: found new least error %d\n", min_e); /* We found good settings -- bail out now */ if (min_e <= dd->rate_tolerance) break; } } if (min_e < 0) { pr_debug("clock: error: target rate or tolerance too low\n"); return ~0; } dd->last_rounded_m = min_e_m; dd->last_rounded_n = min_e_n; dd->last_rounded_rate = _dpll_compute_new_rate(dd->clk_ref->rate, min_e_m, min_e_n); pr_debug("clock: final least error: e = %d, m = %d, n = %d\n", min_e, min_e_m, min_e_n); pr_debug("clock: final rate: %ld (target rate: %ld)\n", dd->last_rounded_rate, target_rate); return dd->last_rounded_rate; } /*------------------------------------------------------------------------- * Omap2 clock reset and init functions *-------------------------------------------------------------------------*/ #ifdef CONFIG_OMAP_RESET_CLOCKS void omap2_clk_disable_unused(struct clk *clk) { u32 regval32, v; v = (clk->flags & INVERT_ENABLE) ? (1 << clk->enable_bit) : 0; regval32 = __raw_readl(clk->enable_reg); if ((regval32 & (1 << clk->enable_bit)) == v) return; printk(KERN_DEBUG "Disabling unused clock \"%s\"\n", clk->name); if (cpu_is_omap34xx()) { omap2_clk_enable(clk); omap2_clk_disable(clk); } else _omap2_clk_disable(clk); if (clk->clkdm != NULL) pwrdm_clkdm_state_switch(clk->clkdm); } #endif