Message-ID: <20240105163651.GJ14858@ediswmail.ad.cirrus.com>
Date: Fri, 5 Jan 2024 16:36:51 +0000
From: Charles Keepax <ckeepax@...nsource.cirrus.com>
To: James Ogletree <jogletre@...nsource.cirrus.com>
CC: James Ogletree <james.ogletree@...rus.com>,
        Fred Treven
	<fred.treven@...rus.com>,
        Ben Bright <ben.bright@...rus.com>,
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Subject: Re: [PATCH v5 1/5] firmware: cs_dsp: Add write sequencer interface

On Thu, Jan 04, 2024 at 10:36:34PM +0000, James Ogletree wrote:
> A write sequencer is a sequence of register addresses
> and values executed by some Cirrus DSPs following
> power-up or exit from hibernation, used for avoiding
> the overhead of bus transactions.
> 
> Add support for Cirrus drivers to update or add to a
> write sequencer present in firmware.
> 
> Signed-off-by: James Ogletree <jogletre@...nsource.cirrus.com>
> ---
>  drivers/firmware/cirrus/cs_dsp.c       | 261 +++++++++++++++++++++++++
>  include/linux/firmware/cirrus/cs_dsp.h |  28 +++
>  2 files changed, 289 insertions(+)
> 
> diff --git a/drivers/firmware/cirrus/cs_dsp.c b/drivers/firmware/cirrus/cs_dsp.c
> index 79d4254d1f9b..31a999f42e84 100644
> --- a/drivers/firmware/cirrus/cs_dsp.c
> +++ b/drivers/firmware/cirrus/cs_dsp.c
> @@ -275,6 +275,15 @@
>  #define HALO_MPU_VIO_ERR_SRC_MASK           0x00007fff
>  #define HALO_MPU_VIO_ERR_SRC_SHIFT                   0
>  
> +/*
> + * Write Sequencer
> + */
> +#define WSEQ_OP_FULL_WORDS	3
> +#define WSEQ_OP_X16_WORDS	2
> +#define WSEQ_OP_END_WORDS	1
> +#define WSEQ_OP_UNLOCK_WORDS	1
> +#define WSEQ_END_OF_SCRIPT	0xFFFFFF
> +
>  struct cs_dsp_ops {
>  	bool (*validate_version)(struct cs_dsp *dsp, unsigned int version);
>  	unsigned int (*parse_sizes)(struct cs_dsp *dsp,
> @@ -2233,6 +2242,111 @@ static int cs_dsp_create_name(struct cs_dsp *dsp)
>  	return 0;
>  }
>  
> +struct cs_dsp_wseq_op {
> +	struct list_head list;
> +	u32 words[3];
> +	u32 address;
> +	u32 data;
> +	u16 offset;
> +	u8 operation;
> +};
> +
> +static int cs_dsp_populate_wseq(struct cs_dsp *dsp, struct cs_dsp_wseq *wseq)
> +{
> +	struct cs_dsp_wseq_op *op = NULL;
> +	struct cs_dsp_chunk ch;
> +	int i, num_words, ret;
> +	u32 *words;
> +
> +	if (wseq->size <= 0 || !wseq->reg)
> +		return -EINVAL;

I would be tempted to give this an error message.

> +
> +	words = kcalloc(wseq->size, sizeof(u32), GFP_KERNEL);
> +	if (!words)
> +		return -ENOMEM;
> +
> +	INIT_LIST_HEAD(&wseq->ops);
> +
> +	ret = regmap_raw_read(dsp->regmap, wseq->reg, words,
> +			      wseq->size * sizeof(u32));
> +	if (ret)
> +		goto err_free;
> +
> +	ch = cs_dsp_chunk(words, wseq->size * sizeof(u32));
> +
> +	for (i = 0; i < wseq->size; i += num_words) {

Can just drop num_words and i, and just do:

	while(!cs_dsp_chunk_end(&ch)) {

Also allows you to drop the length defines for each OP.

> +		op = devm_kzalloc(dsp->dev, sizeof(*op), GFP_KERNEL);
> +		if (!op) {
> +			ret = -ENOMEM;
> +			goto err_free;
> +		}
> +
> +		op->offset = ch.bytes;

Use cs_dsp_chunk_bytes, cleaner to not access the internals
directly incase we need to refactor them at some point.

> +		op->operation = cs_dsp_chunk_read(&ch, 8);
> +
> +		switch (op->operation) {
> +		case CS_DSP_WSEQ_END:
> +			num_words = WSEQ_OP_END_WORDS;
> +			break;
> +		case CS_DSP_WSEQ_UNLOCK:
> +			num_words = WSEQ_OP_UNLOCK_WORDS;
> +			op->address = 0;
> +			op->data = cs_dsp_chunk_read(&ch, 16);
> +			break;
> +		case CS_DSP_WSEQ_ADDR8:
> +		case CS_DSP_WSEQ_H16:
> +		case CS_DSP_WSEQ_L16:
> +			num_words = WSEQ_OP_X16_WORDS;
> +			op->address = cs_dsp_chunk_read(&ch, 24);
> +			op->data = cs_dsp_chunk_read(&ch, 16);
> +			break;
> +		case CS_DSP_WSEQ_FULL:
> +			num_words = WSEQ_OP_FULL_WORDS;
> +			op->address = cs_dsp_chunk_read(&ch, 32);
> +			op->data = cs_dsp_chunk_read(&ch, 32);
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			cs_dsp_err(dsp, "Unsupported op: %u\n", op->operation);
> +			goto err_free;
> +		}
> +
> +		list_add(&op->list, &wseq->ops);
> +
> +		if (op->operation == CS_DSP_WSEQ_END)
> +			break;
> +	}
> +
> +	if (op && op->operation != CS_DSP_WSEQ_END)
> +		ret = -ENOENT;

This definitely wants an error message, since this indicates the
firmware is in a broken state, or the buffer passed in was not a
write sequence.

> +err_free:
> +	kfree(words);
> +
> +	return ret;
> +}
> +
> +/**
> + * cs_dsp_wseq_init() - Initialize write sequences contained within the loaded DSP firmware
> + * @dsp: pointer to DSP structure
> + * @wseqs: list of write sequences to initialize
> + * @num_wseqs: number of write sequences to initialize
> + *
> + * Return: Zero for success, a negative number on error.
> + */
> +int cs_dsp_wseq_init(struct cs_dsp *dsp, struct cs_dsp_wseq *wseqs, unsigned int num_wseqs)
> +{
> +	int i, ret;
> +
> +	for (i = 0; i < num_wseqs; i++) {
> +		ret = cs_dsp_populate_wseq(dsp, &wseqs[i]);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(cs_dsp_wseq_init);
> +

This location in the middle of the file is a bit weird, would be
nicer to keep all the wseq stuff together move this down to the
bottom of the file with the other functions.

>  static int cs_dsp_common_init(struct cs_dsp *dsp)
>  {
>  	int ret;
> @@ -3339,6 +3453,153 @@ int cs_dsp_chunk_read(struct cs_dsp_chunk *ch, int nbits)
>  }
>  EXPORT_SYMBOL_NS_GPL(cs_dsp_chunk_read, FW_CS_DSP);
>  
> +static struct cs_dsp_wseq_op *cs_dsp_wseq_find_op(u8 op_code, u32 addr,
> +						  struct list_head *wseq_ops)
> +{
> +	struct cs_dsp_wseq_op *op;
> +
> +	list_for_each_entry(op, wseq_ops, list) {
> +		if (op->operation == op_code && op->address == addr)
> +			return op;
> +	}
> +
> +	return NULL;
> +}
> +
> +/**
> + * cs_dsp_wseq_write() - Add or update an entry in a write sequence
> + * @dsp: Pointer to a DSP structure
> + * @wseq: Write sequence to write to
> + * @addr: Address of the register to be written to
> + * @data: Data to be written
> + * @update: If true, searches for the first entry in the Write Sequencer with
> + * the same address and op_code, and replaces it. If false, creates a new entry
> + * at the tail.
> + * @op_code: The type of operation of the new entry
> + *
> + * This function formats register address and value pairs into the format
> + * required for write sequence entries, and either updates or adds the
> + * new entry into the write sequence.
> + *
> + * Return: Zero for success, a negative number on error.
> + */
> +int cs_dsp_wseq_write(struct cs_dsp *dsp, struct cs_dsp_wseq *wseq,
> +		      u32 addr, u32 data, bool update, u8 op_code)

Feels weird to have the op_code after the update flag in the
order of arguments. addr, data and op_code are all parts of
the new entry they should go together. Also be nice for the API
to be consistent in the order it uses them, wseq_find_op is
op_code, addr.

> +{
> +	struct cs_dsp_wseq_op *op_end, *op_new;
> +	struct cs_dsp_chunk ch;
> +	u32 wseq_bytes;
> +	int new_op_size, ret;
> +
> +	if (update) {
> +		op_new = cs_dsp_wseq_find_op(op_code, addr, &wseq->ops);
> +		if (!op_new)
> +			return -EINVAL;

This could also have an error message.

> +	} else {

I would be tempted to pull the init of op_end up here like:

		op_end = cs_dsp_wseq_find_op(CS_DSP_WSEQ_END, 0, &wseq->ops);
		if (!op_end) {
			cs_dsp_err(dsp, "Missing write sequencer list terminator\n");
			return -EINVAL;
		}

> +		op_new = devm_kzalloc(dsp->dev, sizeof(*op_new), GFP_KERNEL);
> +		if (!op_new)
> +			return -ENOMEM;
> +
> +		op_new->operation = op_code;
> +		op_new->address = addr;

And:

		op_new->offset = op_end->offset;
> +	}
> +
> +	op_new->data = data;
> +
> +	ch = cs_dsp_chunk((void *) op_new->words,
> +			  WSEQ_OP_FULL_WORDS * sizeof(u32));

Since this is the only place you use op->words make it a local
variable, its only 3 ints on the stack and it saves having 3
redundant ints in every op in the list.

> +	cs_dsp_chunk_write(&ch, 8, op_new->operation);
> +	switch (op_code) {
> +	case CS_DSP_WSEQ_FULL:
> +		cs_dsp_chunk_write(&ch, 32, op_new->address);
> +		cs_dsp_chunk_write(&ch, 32, op_new->data);
> +		break;
> +	case CS_DSP_WSEQ_L16:
> +	case CS_DSP_WSEQ_H16:
> +		cs_dsp_chunk_write(&ch, 24, op_new->address);
> +		cs_dsp_chunk_write(&ch, 16, op_new->data);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		goto op_new_free;

This also could have an error message, in general I would
recommend have error messages for places where handling
arguments from the user of the API. It is much more friendly
for other developers, since they get immediate feedback if
when they do something wrong when using the API.

> +	}
> +

With op_end pre-initialised this bit becomes:

> +	new_op_size = cs_dsp_chunk_bytes(&ch);
> +
> +	wseq_bytes = wseq->size * sizeof(u32);
> +
> +	if (wseq_bytes - op_end->offset < new_op_size) {
> +		cs_dsp_err(dsp, "Not enough memory in Write Sequencer for entry\n");
> +		ret = -ENOMEM;
> +		goto op_new_free;
> +	}
> +
> +	ret = regmap_raw_write(dsp->regmap, wseq->reg + op_new->offset,
> +			       op_new->words, new_op_size);
> +	if (ret)
> +		goto op_new_free;
> +
> +	if (!update) {

Then pull the shift of op_end->offset into here:

		op_end->offset += new_op_size;

> +		ret = regmap_write(dsp->regmap, wseq->reg + op_end->offset,
> +				   WSEQ_END_OF_SCRIPT);
> +		if (ret)
> +			goto op_new_free;
> +
> +		list_add(&op_new->list, &wseq->ops);
> +	}
> +
> +	return 0;
> +
> +op_new_free:
> +	devm_kfree(dsp->dev, op_new);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(cs_dsp_wseq_write);
> +
> +/**
> + * cs_dsp_wseq_multi_write() - Add or update multiple entries in the write sequence
> + * @dsp: Pointer to a DSP structure
> + * @wseq: Write sequence to write to
> + * @reg_seq: List of address-data pairs
> + * @num_regs: Number of address-data pairs
> + * @update: If true, searches for the first entry in the write sequence with the same
> + * address and op code, and replaces it. If false, creates a new entry at the tail.
> + * @op_code: The types of operations of the new entries
> + *
> + * This function calls cs_dsp_wseq_write() for multiple address-data pairs.
> + *
> + * Return: Zero for success, a negative number on error.
> + */
> +int cs_dsp_wseq_multi_write(struct cs_dsp *dsp, struct cs_dsp_wseq *wseq,
> +			    const struct reg_sequence *reg_seq,
> +			    int num_regs, bool update, u8 op_code)
> +{
> +	int ret, i;
> +
> +	for (i = 0; i < num_regs; i++) {
> +		ret = cs_dsp_wseq_write(dsp, wseq, reg_seq[i].reg,
> +					reg_seq[i].def, update, op_code);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(cs_dsp_wseq_multi_write);
> +
>  MODULE_DESCRIPTION("Cirrus Logic DSP Support");
>  MODULE_AUTHOR("Simon Trimmer <simont@...nsource.cirrus.com>");
>  MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/firmware/cirrus/cs_dsp.h b/include/linux/firmware/cirrus/cs_dsp.h
> index 29cd11d5a3cf..d674fc061e9d 100644
> --- a/include/linux/firmware/cirrus/cs_dsp.h
> +++ b/include/linux/firmware/cirrus/cs_dsp.h
> @@ -42,6 +42,16 @@
>  #define CS_DSP_ACKED_CTL_MIN_VALUE           0
>  #define CS_DSP_ACKED_CTL_MAX_VALUE           0xFFFFFF
>  
> +/*
> + * Write sequencer operation codes
> + */
> +#define CS_DSP_WSEQ_FULL	0x00
> +#define CS_DSP_WSEQ_ADDR8	0x02
> +#define CS_DSP_WSEQ_L16		0x04
> +#define CS_DSP_WSEQ_H16		0x05
> +#define CS_DSP_WSEQ_UNLOCK	0xFD
> +#define CS_DSP_WSEQ_END		0xFF
> +
>  /**
>   * struct cs_dsp_region - Describes a logical memory region in DSP address space
>   * @type:	Memory region type
> @@ -107,6 +117,18 @@ struct cs_dsp_coeff_ctl {
>  struct cs_dsp_ops;
>  struct cs_dsp_client_ops;
>  
> +/**
> + * struct cs_dsp_wseq - Describes a write sequence
> + * @reg:	Address of the head of the write sequence register
> + * @size:	Size of the write sequence in words

The only user that wants the size in words is the loop counter
that can be deleted. Is there any reason not to specify the
size in bytes?

> + * @ops:	Operations contained within the write sequence
> + */
> +struct cs_dsp_wseq {
> +	unsigned int reg;
> +	unsigned int size;
> +	struct list_head ops;
> +};
> +
>  /**
>   * struct cs_dsp - Configuration and state of a Cirrus Logic DSP
>   * @name:		The name of the DSP instance
> @@ -254,6 +276,12 @@ struct cs_dsp_alg_region *cs_dsp_find_alg_region(struct cs_dsp *dsp,
>  						 int type, unsigned int id);
>  
>  const char *cs_dsp_mem_region_name(unsigned int type);
> +int cs_dsp_wseq_init(struct cs_dsp *dsp, struct cs_dsp_wseq *wseqs, unsigned int num_wseqs);
> +int cs_dsp_wseq_write(struct cs_dsp *dsp, struct cs_dsp_wseq *wseq, u32 addr, u32 data,
> +		      bool update, u8 op_code);
> +int cs_dsp_wseq_multi_write(struct cs_dsp *dsp, struct cs_dsp_wseq *wseq,
> +			    const struct reg_sequence *reg_seq,
> +			    int num_regs, bool update, u8 op_code);
>  

This is also pretty spaced through the file, leave the defines
where they are, but gather the struct and the funcs and move
them to the bottom of the file in a group. Keeps all the API
together when someone is looking it up.

>  /**
>   * struct cs_dsp_chunk - Describes a buffer holding data formatted for the DSP
> -- 
> 2.25.1
> 

Overall my only other concern is still the register based API
rather than control based. I guess there is some precident
with the compressed stuff although that is at least taking
addresses from the DSP and translating them into register
addresses so the host can use them.

Richard is off today, but back on Monday let me discuss with
him then and we should have a chat too.

Thanks,
Charles

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