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404 lines
9.5 KiB
404 lines
9.5 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Driver for Silicon Labs Si514 Programmable Oscillator |
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* |
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* Copyright (C) 2015 Topic Embedded Products |
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* |
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* Author: Mike Looijmans <[email protected]> |
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*/ |
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#include <linux/clk-provider.h> |
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#include <linux/delay.h> |
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#include <linux/module.h> |
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#include <linux/i2c.h> |
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#include <linux/regmap.h> |
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#include <linux/slab.h> |
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/* I2C registers */ |
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#define SI514_REG_LP 0 |
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#define SI514_REG_M_FRAC1 5 |
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#define SI514_REG_M_FRAC2 6 |
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#define SI514_REG_M_FRAC3 7 |
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#define SI514_REG_M_INT_FRAC 8 |
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#define SI514_REG_M_INT 9 |
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#define SI514_REG_HS_DIV 10 |
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#define SI514_REG_LS_HS_DIV 11 |
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#define SI514_REG_OE_STATE 14 |
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#define SI514_REG_RESET 128 |
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#define SI514_REG_CONTROL 132 |
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/* Register values */ |
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#define SI514_RESET_RST BIT(7) |
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#define SI514_CONTROL_FCAL BIT(0) |
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#define SI514_CONTROL_OE BIT(2) |
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#define SI514_MIN_FREQ 100000U |
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#define SI514_MAX_FREQ 250000000U |
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#define FXO 31980000U |
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#define FVCO_MIN 2080000000U |
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#define FVCO_MAX 2500000000U |
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#define HS_DIV_MAX 1022 |
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struct clk_si514 { |
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struct clk_hw hw; |
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struct regmap *regmap; |
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struct i2c_client *i2c_client; |
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}; |
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#define to_clk_si514(_hw) container_of(_hw, struct clk_si514, hw) |
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/* Multiplier/divider settings */ |
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struct clk_si514_muldiv { |
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u32 m_frac; /* 29-bit Fractional part of multiplier M */ |
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u8 m_int; /* Integer part of multiplier M, 65..78 */ |
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u8 ls_div_bits; /* 2nd divider, as 2^x */ |
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u16 hs_div; /* 1st divider, must be even and 10<=x<=1022 */ |
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}; |
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/* Enables or disables the output driver */ |
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static int si514_enable_output(struct clk_si514 *data, bool enable) |
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{ |
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return regmap_update_bits(data->regmap, SI514_REG_CONTROL, |
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SI514_CONTROL_OE, enable ? SI514_CONTROL_OE : 0); |
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} |
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static int si514_prepare(struct clk_hw *hw) |
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{ |
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struct clk_si514 *data = to_clk_si514(hw); |
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return si514_enable_output(data, true); |
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} |
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static void si514_unprepare(struct clk_hw *hw) |
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{ |
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struct clk_si514 *data = to_clk_si514(hw); |
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si514_enable_output(data, false); |
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} |
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static int si514_is_prepared(struct clk_hw *hw) |
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{ |
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struct clk_si514 *data = to_clk_si514(hw); |
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unsigned int val; |
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int err; |
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err = regmap_read(data->regmap, SI514_REG_CONTROL, &val); |
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if (err < 0) |
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return err; |
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return !!(val & SI514_CONTROL_OE); |
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} |
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/* Retrieve clock multiplier and dividers from hardware */ |
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static int si514_get_muldiv(struct clk_si514 *data, |
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struct clk_si514_muldiv *settings) |
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{ |
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int err; |
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u8 reg[7]; |
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err = regmap_bulk_read(data->regmap, SI514_REG_M_FRAC1, |
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reg, ARRAY_SIZE(reg)); |
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if (err) |
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return err; |
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settings->m_frac = reg[0] | reg[1] << 8 | reg[2] << 16 | |
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(reg[3] & 0x1F) << 24; |
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settings->m_int = (reg[4] & 0x3f) << 3 | reg[3] >> 5; |
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settings->ls_div_bits = (reg[6] >> 4) & 0x07; |
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settings->hs_div = (reg[6] & 0x03) << 8 | reg[5]; |
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return 0; |
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} |
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static int si514_set_muldiv(struct clk_si514 *data, |
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struct clk_si514_muldiv *settings) |
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{ |
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u8 lp; |
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u8 reg[7]; |
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int err; |
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/* Calculate LP1/LP2 according to table 13 in the datasheet */ |
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/* 65.259980246 */ |
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if (settings->m_int < 65 || |
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(settings->m_int == 65 && settings->m_frac <= 139575831)) |
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lp = 0x22; |
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/* 67.859763463 */ |
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else if (settings->m_int < 67 || |
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(settings->m_int == 67 && settings->m_frac <= 461581994)) |
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lp = 0x23; |
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/* 72.937624981 */ |
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else if (settings->m_int < 72 || |
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(settings->m_int == 72 && settings->m_frac <= 503383578)) |
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lp = 0x33; |
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/* 75.843265046 */ |
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else if (settings->m_int < 75 || |
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(settings->m_int == 75 && settings->m_frac <= 452724474)) |
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lp = 0x34; |
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else |
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lp = 0x44; |
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err = regmap_write(data->regmap, SI514_REG_LP, lp); |
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if (err < 0) |
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return err; |
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reg[0] = settings->m_frac; |
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reg[1] = settings->m_frac >> 8; |
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reg[2] = settings->m_frac >> 16; |
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reg[3] = settings->m_frac >> 24 | settings->m_int << 5; |
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reg[4] = settings->m_int >> 3; |
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reg[5] = settings->hs_div; |
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reg[6] = (settings->hs_div >> 8) | (settings->ls_div_bits << 4); |
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err = regmap_bulk_write(data->regmap, SI514_REG_HS_DIV, reg + 5, 2); |
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if (err < 0) |
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return err; |
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/* |
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* Writing to SI514_REG_M_INT_FRAC triggers the clock change, so that |
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* must be written last |
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*/ |
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return regmap_bulk_write(data->regmap, SI514_REG_M_FRAC1, reg, 5); |
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} |
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/* Calculate divider settings for a given frequency */ |
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static int si514_calc_muldiv(struct clk_si514_muldiv *settings, |
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unsigned long frequency) |
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{ |
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u64 m; |
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u32 ls_freq; |
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u32 tmp; |
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u8 res; |
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if ((frequency < SI514_MIN_FREQ) || (frequency > SI514_MAX_FREQ)) |
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return -EINVAL; |
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/* Determine the minimum value of LS_DIV and resulting target freq. */ |
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ls_freq = frequency; |
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if (frequency >= (FVCO_MIN / HS_DIV_MAX)) |
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settings->ls_div_bits = 0; |
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else { |
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res = 1; |
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tmp = 2 * HS_DIV_MAX; |
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while (tmp <= (HS_DIV_MAX * 32)) { |
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if ((frequency * tmp) >= FVCO_MIN) |
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break; |
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++res; |
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tmp <<= 1; |
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} |
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settings->ls_div_bits = res; |
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ls_freq = frequency << res; |
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} |
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/* Determine minimum HS_DIV, round up to even number */ |
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settings->hs_div = DIV_ROUND_UP(FVCO_MIN >> 1, ls_freq) << 1; |
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/* M = LS_DIV x HS_DIV x frequency / F_XO (in fixed-point) */ |
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m = ((u64)(ls_freq * settings->hs_div) << 29) + (FXO / 2); |
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do_div(m, FXO); |
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settings->m_frac = (u32)m & (BIT(29) - 1); |
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settings->m_int = (u32)(m >> 29); |
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return 0; |
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} |
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/* Calculate resulting frequency given the register settings */ |
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static unsigned long si514_calc_rate(struct clk_si514_muldiv *settings) |
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{ |
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u64 m = settings->m_frac | ((u64)settings->m_int << 29); |
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u32 d = settings->hs_div * BIT(settings->ls_div_bits); |
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return ((u32)(((m * FXO) + (FXO / 2)) >> 29)) / d; |
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} |
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static unsigned long si514_recalc_rate(struct clk_hw *hw, |
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unsigned long parent_rate) |
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{ |
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struct clk_si514 *data = to_clk_si514(hw); |
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struct clk_si514_muldiv settings; |
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int err; |
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err = si514_get_muldiv(data, &settings); |
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if (err) { |
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dev_err(&data->i2c_client->dev, "unable to retrieve settings\n"); |
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return 0; |
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} |
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return si514_calc_rate(&settings); |
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} |
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static long si514_round_rate(struct clk_hw *hw, unsigned long rate, |
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unsigned long *parent_rate) |
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{ |
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struct clk_si514_muldiv settings; |
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int err; |
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if (!rate) |
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return 0; |
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err = si514_calc_muldiv(&settings, rate); |
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if (err) |
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return err; |
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return si514_calc_rate(&settings); |
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} |
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/* |
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* Update output frequency for big frequency changes (> 1000 ppm). |
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* The chip supports <1000ppm changes "on the fly", we haven't implemented |
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* that here. |
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*/ |
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static int si514_set_rate(struct clk_hw *hw, unsigned long rate, |
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unsigned long parent_rate) |
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{ |
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struct clk_si514 *data = to_clk_si514(hw); |
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struct clk_si514_muldiv settings; |
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unsigned int old_oe_state; |
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int err; |
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err = si514_calc_muldiv(&settings, rate); |
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if (err) |
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return err; |
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err = regmap_read(data->regmap, SI514_REG_CONTROL, &old_oe_state); |
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if (err) |
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return err; |
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si514_enable_output(data, false); |
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err = si514_set_muldiv(data, &settings); |
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if (err < 0) |
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return err; /* Undefined state now, best to leave disabled */ |
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/* Trigger calibration */ |
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err = regmap_write(data->regmap, SI514_REG_CONTROL, SI514_CONTROL_FCAL); |
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if (err < 0) |
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return err; |
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/* Applying a new frequency can take up to 10ms */ |
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usleep_range(10000, 12000); |
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if (old_oe_state & SI514_CONTROL_OE) |
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si514_enable_output(data, true); |
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return err; |
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} |
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static const struct clk_ops si514_clk_ops = { |
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.prepare = si514_prepare, |
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.unprepare = si514_unprepare, |
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.is_prepared = si514_is_prepared, |
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.recalc_rate = si514_recalc_rate, |
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.round_rate = si514_round_rate, |
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.set_rate = si514_set_rate, |
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}; |
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static bool si514_regmap_is_volatile(struct device *dev, unsigned int reg) |
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{ |
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switch (reg) { |
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case SI514_REG_CONTROL: |
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case SI514_REG_RESET: |
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return true; |
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default: |
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return false; |
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} |
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} |
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static bool si514_regmap_is_writeable(struct device *dev, unsigned int reg) |
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{ |
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switch (reg) { |
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case SI514_REG_LP: |
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case SI514_REG_M_FRAC1 ... SI514_REG_LS_HS_DIV: |
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case SI514_REG_OE_STATE: |
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case SI514_REG_RESET: |
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case SI514_REG_CONTROL: |
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return true; |
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default: |
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return false; |
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} |
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} |
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static const struct regmap_config si514_regmap_config = { |
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.reg_bits = 8, |
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.val_bits = 8, |
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.cache_type = REGCACHE_RBTREE, |
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.max_register = SI514_REG_CONTROL, |
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.writeable_reg = si514_regmap_is_writeable, |
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.volatile_reg = si514_regmap_is_volatile, |
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}; |
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static int si514_probe(struct i2c_client *client) |
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{ |
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struct clk_si514 *data; |
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struct clk_init_data init; |
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int err; |
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data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); |
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if (!data) |
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return -ENOMEM; |
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init.ops = &si514_clk_ops; |
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init.flags = 0; |
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init.num_parents = 0; |
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data->hw.init = &init; |
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data->i2c_client = client; |
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if (of_property_read_string(client->dev.of_node, "clock-output-names", |
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&init.name)) |
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init.name = client->dev.of_node->name; |
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data->regmap = devm_regmap_init_i2c(client, &si514_regmap_config); |
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if (IS_ERR(data->regmap)) { |
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dev_err(&client->dev, "failed to allocate register map\n"); |
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return PTR_ERR(data->regmap); |
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} |
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i2c_set_clientdata(client, data); |
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err = devm_clk_hw_register(&client->dev, &data->hw); |
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if (err) { |
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dev_err(&client->dev, "clock registration failed\n"); |
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return err; |
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} |
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err = of_clk_add_hw_provider(client->dev.of_node, of_clk_hw_simple_get, |
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&data->hw); |
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if (err) { |
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dev_err(&client->dev, "unable to add clk provider\n"); |
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return err; |
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} |
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return 0; |
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} |
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static int si514_remove(struct i2c_client *client) |
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{ |
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of_clk_del_provider(client->dev.of_node); |
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return 0; |
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} |
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static const struct i2c_device_id si514_id[] = { |
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{ "si514", 0 }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(i2c, si514_id); |
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static const struct of_device_id clk_si514_of_match[] = { |
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{ .compatible = "silabs,si514" }, |
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{ }, |
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}; |
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MODULE_DEVICE_TABLE(of, clk_si514_of_match); |
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static struct i2c_driver si514_driver = { |
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.driver = { |
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.name = "si514", |
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.of_match_table = clk_si514_of_match, |
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}, |
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.probe_new = si514_probe, |
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.remove = si514_remove, |
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.id_table = si514_id, |
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}; |
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module_i2c_driver(si514_driver); |
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MODULE_AUTHOR("Mike Looijmans <[email protected]>"); |
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MODULE_DESCRIPTION("Si514 driver"); |
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MODULE_LICENSE("GPL");
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