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Commit 392ba5fa authored by Chen-Yu Tsai's avatar Chen-Yu Tsai Committed by Maxime Ripard
Browse files

clk: sunxi-ng: nm: Add support for sigma-delta modulation 



Some of the N-M-style clocks, namely the PLLs, support sigma-delta
modulation to do fractional-N frequency synthesis. This is used in
the audio PLL to generate the exact frequency the audio blocks need.
These frequencies can not be generated with integer N-M factors.

Signed-off-by: default avatarChen-Yu Tsai <wens@csie.org>
Signed-off-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
parent 05d2eaac

drivers/clk/sunxi-ng/ccu_nm.c

+21 −1
Original line number Diff line number Diff line
@@ -90,6 +90,14 @@ static unsigned long ccu_nm_recalc_rate(struct clk_hw *hw, 
	if (!m)

		m++;



	if (ccu_sdm_helper_is_enabled(&nm->common, &nm->sdm)) {

		unsigned long rate =

			ccu_sdm_helper_read_rate(&nm->common, &nm->sdm,

						 m, n);

		if (rate)

			return rate;

	}



	return parent_rate * n / m;

}
@@ -102,6 +110,9 @@ static long ccu_nm_round_rate(struct clk_hw *hw, unsigned long rate, 
	if (ccu_frac_helper_has_rate(&nm->common, &nm->frac, rate))

		return rate;



	if (ccu_sdm_helper_has_rate(&nm->common, &nm->sdm, rate))

		return rate;



	_nm.min_n = nm->n.min ?: 1;

	_nm.max_n = nm->n.max ?: 1 << nm->n.width;

	_nm.min_m = 1;
@@ -143,7 +154,16 @@ static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long rate, 
	_nm.min_m = 1;

	_nm.max_m = nm->m.max ?: 1 << nm->m.width;



	if (ccu_sdm_helper_has_rate(&nm->common, &nm->sdm, rate)) {

		ccu_sdm_helper_enable(&nm->common, &nm->sdm, rate);



		/* Sigma delta modulation requires specific N and M factors */

		ccu_sdm_helper_get_factors(&nm->common, &nm->sdm, rate,

					   &_nm.m, &_nm.n);

	} else {

		ccu_sdm_helper_disable(&nm->common, &nm->sdm);

		ccu_nm_find_best(parent_rate, rate, &_nm);

	}



	spin_lock_irqsave(nm->common.lock, flags);

drivers/clk/sunxi-ng/ccu_nm.h

+25 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include "ccu_div.h"

#include "ccu_frac.h"

#include "ccu_mult.h"

#include "ccu_sdm.h"



/*

 * struct ccu_nm - Definition of an N-M clock
@@ -33,10 +34,34 @@ struct ccu_nm { 
	struct ccu_mult_internal	n;

	struct ccu_div_internal		m;

	struct ccu_frac_internal	frac;

	struct ccu_sdm_internal		sdm;



	struct ccu_common	common;

};



#define SUNXI_CCU_NM_WITH_SDM_GATE_LOCK(_struct, _name, _parent, _reg,	\

					_nshift, _nwidth,		\

					_mshift, _mwidth,		\

					_sdm_table, _sdm_en,		\

					_sdm_reg, _sdm_reg_en,		\

					_gate, _lock, _flags)		\

	struct ccu_nm _struct = {					\

		.enable		= _gate,				\

		.lock		= _lock,				\

		.n		= _SUNXI_CCU_MULT(_nshift, _nwidth),	\

		.m		= _SUNXI_CCU_DIV(_mshift, _mwidth),	\

		.sdm		= _SUNXI_CCU_SDM(_sdm_table, _sdm_en,	\

						 _sdm_reg, _sdm_reg_en),\

		.common		= {					\

			.reg		= _reg,				\

			.features	= CCU_FEATURE_SIGMA_DELTA_MOD,	\

			.hw.init	= CLK_HW_INIT(_name,		\

						      _parent,		\

						      &ccu_nm_ops,	\

						      _flags),		\

		},							\

	}



#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK(_struct, _name, _parent, _reg,	\

					 _nshift, _nwidth,		\

					 _mshift, _mwidth,		\