soundwire: Add generic bandwidth allocation algorithm

This algorithm computes bus parameters like clock frequency, frame
shape and port transport parameters based on active stream(s) running
on the bus.

Developers can also implement their own .compute_params() callback for
specific resource management algorithm, and set if before calling
sdw_add_bus_master()

Credits: this patch is based on an earlier internal contribution by
Vinod Koul, Sanyog Kale, Shreyas Nc and Hardik Shah. All hard-coded
values were removed from the initial contribution to use BIOS
information instead.

Signed-off-by: Bard Liao <[e-mail]>
Acked-by: Jaroslav Kysela <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/soundwire/Kconfig

···
 config SOUNDWIRE_INTEL
 	tristate "Intel SoundWire Master driver"
 	select SOUNDWIRE_CADENCE
+	select SOUNDWIRE_GENERIC_ALLOCATION
 	depends on ACPI && SND_SOC
 	help
 	  SoundWire Intel Master driver.
···
 	  If you have an Qualcomm platform which has a SoundWire Master then
 	  enable this config option to get the SoundWire support for that
 	  device
+
+config SOUNDWIRE_GENERIC_ALLOCATION
+	tristate
+
 endif

drivers/soundwire/Makefile

···
 			sysfs_slave.o sysfs_slave_dpn.o
 obj-$(CONFIG_SOUNDWIRE) += soundwire-bus.o
 
+soundwire-generic-allocation-objs := generic_bandwidth_allocation.o
+obj-$(CONFIG_SOUNDWIRE_GENERIC_ALLOCATION) += soundwire-generic-allocation.o
+
 ifdef CONFIG_DEBUG_FS
 soundwire-bus-y += debugfs.o
 endif

drivers/soundwire/bus.c

···
 		return -EINVAL;
 	}
 
+	if (!bus->compute_params) {
+		dev_err(bus->dev,
+			"Bandwidth allocation not configured, compute_params no set\n");
+		return -EINVAL;
+	}
+
 	mutex_init(&bus->msg_lock);
 	mutex_init(&bus->bus_lock);
 	INIT_LIST_HEAD(&bus->slaves);

drivers/soundwire/bus.h

···
 };
 
 #define SDW_DOUBLE_RATE_FACTOR		2
+#define SDW_STRM_RATE_GROUPING		1
 
 extern int sdw_rows[SDW_FRAME_ROWS];
 extern int sdw_cols[SDW_FRAME_COLS];
···
 int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
 		 u32 addr, size_t count, u16 dev_num, u8 flags, u8 *buf);
 
+/* Retrieve and return channel count from channel mask */
+static inline int sdw_ch_mask_to_ch(int ch_mask)
+{
+	int c = 0;
+
+	for (c = 0; ch_mask; ch_mask >>= 1)
+		c += ch_mask & 1;
+
+	return c;
+}
+
+/* Fill transport parameter data structure */
+static inline void sdw_fill_xport_params(struct sdw_transport_params *params,
+					 int port_num, bool grp_ctrl_valid,
+					 int grp_ctrl, int sample_int,
+					 int off1, int off2,
+					 int hstart, int hstop,
+					 int pack_mode, int lane_ctrl)
+{
+	params->port_num = port_num;
+	params->blk_grp_ctrl_valid = grp_ctrl_valid;
+	params->blk_grp_ctrl = grp_ctrl;
+	params->sample_interval = sample_int;
+	params->offset1 = off1;
+	params->offset2 = off2;
+	params->hstart = hstart;
+	params->hstop = hstop;
+	params->blk_pkg_mode = pack_mode;
+	params->lane_ctrl = lane_ctrl;
+}
+
+/* Fill port parameter data structure */
+static inline void sdw_fill_port_params(struct sdw_port_params *params,
+					int port_num, int bps,
+					int flow_mode, int data_mode)
+{
+	params->num = port_num;
+	params->bps = bps;
+	params->flow_mode = flow_mode;
+	params->data_mode = data_mode;
+}
+
 /* Read-Modify-Write Slave register */
-static inline int
-sdw_update(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
+static inline int sdw_update(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
 {
 	int tmp;
 

drivers/soundwire/generic_bandwidth_allocation.c

···
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+// Copyright(c) 2015-2020 Intel Corporation.
+
+/*
+ * Bandwidth management algorithm based on 2^n gears
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/slab.h>
+#include <linux/soundwire/sdw.h>
+#include "bus.h"
+
+#define SDW_STRM_RATE_GROUPING		1
+
+struct sdw_group_params {
+	unsigned int rate;
+	int full_bw;
+	int payload_bw;
+	int hwidth;
+};
+
+struct sdw_group {
+	unsigned int count;
+	unsigned int max_size;
+	unsigned int *rates;
+};
+
+struct sdw_transport_data {
+	int hstart;
+	int hstop;
+	int block_offset;
+	int sub_block_offset;
+};
+
+static void sdw_compute_slave_ports(struct sdw_master_runtime *m_rt,
+				    struct sdw_transport_data *t_data)
+{
+	struct sdw_slave_runtime *s_rt = NULL;
+	struct sdw_port_runtime *p_rt;
+	int port_bo, sample_int;
+	unsigned int rate, bps, ch = 0;
+	unsigned int slave_total_ch;
+
+	port_bo = t_data->block_offset;
+
+	list_for_each_entry(s_rt, &m_rt->slave_rt_list, m_rt_node) {
+		rate = m_rt->stream->params.rate;
+		bps = m_rt->stream->params.bps;
+		sample_int = (m_rt->bus->params.curr_dr_freq / rate);
+		slave_total_ch = 0;
+
+		list_for_each_entry(p_rt, &s_rt->port_list, port_node) {
+			ch = sdw_ch_mask_to_ch(p_rt->ch_mask);
+
+			sdw_fill_xport_params(&p_rt->transport_params,
+					      p_rt->num, false,
+					      SDW_BLK_GRP_CNT_1,
+					      sample_int, port_bo, port_bo >> 8,
+					      t_data->hstart,
+					      t_data->hstop,
+					      (SDW_BLK_GRP_CNT_1 * ch), 0x0);
+
+			sdw_fill_port_params(&p_rt->port_params,
+					     p_rt->num, bps,
+					     SDW_PORT_FLOW_MODE_ISOCH,
+					     SDW_PORT_DATA_MODE_NORMAL);
+
+			port_bo += bps * ch;
+			slave_total_ch += ch;
+		}
+
+		if (m_rt->direction == SDW_DATA_DIR_TX &&
+		    m_rt->ch_count == slave_total_ch) {
+			/*
+			 * Slave devices were configured to access all channels
+			 * of the stream, which indicates that they operate in
+			 * 'mirror mode'. Make sure we reset the port offset for
+			 * the next device in the list
+			 */
+			port_bo = t_data->block_offset;
+		}
+	}
+}
+
+static void sdw_compute_master_ports(struct sdw_master_runtime *m_rt,
+				     struct sdw_group_params *params,
+				     int port_bo, int hstop)
+{
+	struct sdw_transport_data t_data = {0};
+	struct sdw_port_runtime *p_rt;
+	struct sdw_bus *bus = m_rt->bus;
+	int sample_int, hstart = 0;
+	unsigned int rate, bps, ch, no_ch;
+
+	rate = m_rt->stream->params.rate;
+	bps = m_rt->stream->params.bps;
+	ch = m_rt->ch_count;
+	sample_int = (bus->params.curr_dr_freq / rate);
+
+	if (rate != params->rate)
+		return;
+
+	t_data.hstop = hstop;
+	hstart = hstop - params->hwidth + 1;
+	t_data.hstart = hstart;
+
+	list_for_each_entry(p_rt, &m_rt->port_list, port_node) {
+		no_ch = sdw_ch_mask_to_ch(p_rt->ch_mask);
+
+		sdw_fill_xport_params(&p_rt->transport_params, p_rt->num,
+				      false, SDW_BLK_GRP_CNT_1, sample_int,
+				      port_bo, port_bo >> 8, hstart, hstop,
+				      (SDW_BLK_GRP_CNT_1 * no_ch), 0x0);
+
+		sdw_fill_port_params(&p_rt->port_params,
+				     p_rt->num, bps,
+				     SDW_PORT_FLOW_MODE_ISOCH,
+				     SDW_PORT_DATA_MODE_NORMAL);
+
+		/* Check for first entry */
+		if (!(p_rt == list_first_entry(&m_rt->port_list,
+					       struct sdw_port_runtime,
+					       port_node))) {
+			port_bo += bps * ch;
+			continue;
+		}
+
+		t_data.hstart = hstart;
+		t_data.hstop = hstop;
+		t_data.block_offset = port_bo;
+		t_data.sub_block_offset = 0;
+		port_bo += bps * ch;
+	}
+
+	sdw_compute_slave_ports(m_rt, &t_data);
+}
+
+static void _sdw_compute_port_params(struct sdw_bus *bus,
+				     struct sdw_group_params *params, int count)
+{
+	struct sdw_master_runtime *m_rt = NULL;
+	int hstop = bus->params.col - 1;
+	int block_offset, port_bo, i;
+
+	/* Run loop for all groups to compute transport parameters */
+	for (i = 0; i < count; i++) {
+		port_bo = 1;
+		block_offset = 1;
+
+		list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
+			sdw_compute_master_ports(m_rt, &params[i],
+						 port_bo, hstop);
+
+			block_offset += m_rt->ch_count *
+					m_rt->stream->params.bps;
+			port_bo = block_offset;
+		}
+
+		hstop = hstop - params[i].hwidth;
+	}
+}
+
+static int sdw_compute_group_params(struct sdw_bus *bus,
+				    struct sdw_group_params *params,
+				    int *rates, int count)
+{
+	struct sdw_master_runtime *m_rt = NULL;
+	int sel_col = bus->params.col;
+	unsigned int rate, bps, ch;
+	int i, column_needed = 0;
+
+	/* Calculate bandwidth per group */
+	for (i = 0; i < count; i++) {
+		params[i].rate = rates[i];
+		params[i].full_bw = bus->params.curr_dr_freq / params[i].rate;
+	}
+
+	list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
+		rate = m_rt->stream->params.rate;
+		bps = m_rt->stream->params.bps;
+		ch = m_rt->ch_count;
+
+		for (i = 0; i < count; i++) {
+			if (rate == params[i].rate)
+				params[i].payload_bw += bps * ch;
+		}
+	}
+
+	for (i = 0; i < count; i++) {
+		params[i].hwidth = (sel_col *
+			params[i].payload_bw + params[i].full_bw - 1) /
+			params[i].full_bw;
+
+		column_needed += params[i].hwidth;
+	}
+
+	if (column_needed > sel_col - 1)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int sdw_add_element_group_count(struct sdw_group *group,
+				       unsigned int rate)
+{
+	int num = group->count;
+	int i;
+
+	for (i = 0; i <= num; i++) {
+		if (rate == group->rates[i])
+			break;
+
+		if (i != num)
+			continue;
+
+		if (group->count >= group->max_size) {
+			unsigned int *rates;
+
+			group->max_size += 1;
+			rates = krealloc(group->rates,
+					 (sizeof(int) * group->max_size),
+					 GFP_KERNEL);
+			if (!rates)
+				return -ENOMEM;
+			group->rates = rates;
+		}
+
+		group->rates[group->count++] = rate;
+	}
+
+	return 0;
+}
+
+static int sdw_get_group_count(struct sdw_bus *bus,
+			       struct sdw_group *group)
+{
+	struct sdw_master_runtime *m_rt;
+	unsigned int rate;
+	int ret = 0;
+
+	group->count = 0;
+	group->max_size = SDW_STRM_RATE_GROUPING;
+	group->rates = kcalloc(group->max_size, sizeof(int), GFP_KERNEL);
+	if (!group->rates)
+		return -ENOMEM;
+
+	list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
+		rate = m_rt->stream->params.rate;
+		if (m_rt == list_first_entry(&bus->m_rt_list,
+					     struct sdw_master_runtime,
+					     bus_node)) {
+			group->rates[group->count++] = rate;
+
+		} else {
+			ret = sdw_add_element_group_count(group, rate);
+			if (ret < 0) {
+				kfree(group->rates);
+				return ret;
+			}
+		}
+	}
+
+	return ret;
+}
+
+/**
+ * sdw_compute_port_params: Compute transport and port parameters
+ *
+ * @bus: SDW Bus instance
+ */
+static int sdw_compute_port_params(struct sdw_bus *bus)
+{
+	struct sdw_group_params *params = NULL;
+	struct sdw_group group;
+	int ret;
+
+	ret = sdw_get_group_count(bus, &group);
+	if (ret < 0)
+		return ret;
+
+	if (group.count == 0)
+		goto out;
+
+	params = kcalloc(group.count, sizeof(*params), GFP_KERNEL);
+	if (!params) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	/* Compute transport parameters for grouped streams */
+	ret = sdw_compute_group_params(bus, params,
+				       &group.rates[0], group.count);
+	if (ret < 0)
+		goto free_params;
+
+	_sdw_compute_port_params(bus, params, group.count);
+
+free_params:
+	kfree(params);
+out:
+	kfree(group.rates);
+
+	return ret;
+}
+
+static int sdw_select_row_col(struct sdw_bus *bus, int clk_freq)
+{
+	struct sdw_master_prop *prop = &bus->prop;
+	int frame_int, frame_freq;
+	int r, c;
+
+	for (c = 0; c < SDW_FRAME_COLS; c++) {
+		for (r = 0; r < SDW_FRAME_ROWS; r++) {
+			if (sdw_rows[r] != prop->default_row ||
+			    sdw_cols[c] != prop->default_col)
+				continue;
+
+			frame_int = sdw_rows[r] * sdw_cols[c];
+			frame_freq = clk_freq / frame_int;
+
+			if ((clk_freq - (frame_freq * SDW_FRAME_CTRL_BITS)) <
+			    bus->params.bandwidth)
+				continue;
+
+			bus->params.row = sdw_rows[r];
+			bus->params.col = sdw_cols[c];
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * sdw_compute_bus_params: Compute bus parameters
+ *
+ * @bus: SDW Bus instance
+ */
+static int sdw_compute_bus_params(struct sdw_bus *bus)
+{
+	unsigned int max_dr_freq, curr_dr_freq = 0;
+	struct sdw_master_prop *mstr_prop = NULL;
+	int i, clk_values, ret;
+	bool is_gear = false;
+	u32 *clk_buf;
+
+	mstr_prop = &bus->prop;
+	if (!mstr_prop)
+		return -EINVAL;
+
+	if (mstr_prop->num_clk_gears) {
+		clk_values = mstr_prop->num_clk_gears;
+		clk_buf = mstr_prop->clk_gears;
+		is_gear = true;
+	} else if (mstr_prop->num_clk_freq) {
+		clk_values = mstr_prop->num_clk_freq;
+		clk_buf = mstr_prop->clk_freq;
+	} else {
+		clk_values = 1;
+		clk_buf = NULL;
+	}
+
+	max_dr_freq = mstr_prop->max_clk_freq * SDW_DOUBLE_RATE_FACTOR;
+
+	for (i = 0; i < clk_values; i++) {
+		if (!clk_buf)
+			curr_dr_freq = max_dr_freq;
+		else
+			curr_dr_freq = (is_gear) ?
+				(max_dr_freq >>  clk_buf[i]) :
+				clk_buf[i] * SDW_DOUBLE_RATE_FACTOR;
+
+		if (curr_dr_freq <= bus->params.bandwidth)
+			continue;
+
+		break;
+
+		/*
+		 * TODO: Check all the Slave(s) port(s) audio modes and find
+		 * whether given clock rate is supported with glitchless
+		 * transition.
+		 */
+	}
+
+	if (i == clk_values)
+		return -EINVAL;
+
+	ret = sdw_select_row_col(bus, curr_dr_freq);
+	if (ret < 0)
+		return -EINVAL;
+
+	bus->params.curr_dr_freq = curr_dr_freq;
+	return 0;
+}
+
+/**
+ * sdw_compute_params: Compute bus, transport and port parameters
+ *
+ * @bus: SDW Bus instance
+ */
+int sdw_compute_params(struct sdw_bus *bus)
+{
+	int ret;
+
+	/* Computes clock frequency, frame shape and frame frequency */
+	ret = sdw_compute_bus_params(bus);
+	if (ret < 0) {
+		dev_err(bus->dev, "Compute bus params failed: %d", ret);
+		return ret;
+	}
+
+	/* Compute transport and port params */
+	ret = sdw_compute_port_params(bus);
+	if (ret < 0) {
+		dev_err(bus->dev, "Compute transport params failed: %d", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sdw_compute_params);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_DESCRIPTION("SoundWire Generic Bandwidth Allocation");

drivers/soundwire/intel.c

···
 	/* set driver data, accessed by snd_soc_dai_get_drvdata() */
 	dev_set_drvdata(dev, cdns);
 
+	/* use generic bandwidth allocation algorithm */
+	sdw->cdns.bus.compute_params = sdw_compute_params;
+
 	ret = sdw_bus_master_add(bus, dev, dev->fwnode);
 	if (ret) {
 		dev_err(dev, "sdw_bus_master_add fail: %d\n", ret);

drivers/soundwire/stream.c

···
 int sdw_rows[SDW_FRAME_ROWS] = {48, 50, 60, 64, 75, 80, 125, 147,
 			96, 100, 120, 128, 150, 160, 250, 0,
 			192, 200, 240, 256, 72, 144, 90, 180};
+EXPORT_SYMBOL(sdw_rows);
 
 int sdw_cols[SDW_FRAME_COLS] = {2, 4, 6, 8, 10, 12, 14, 16};
+EXPORT_SYMBOL(sdw_cols);
 
 int sdw_find_col_index(int col)
 {
···
 		/* TODO: Update this during Device-Device support */
 		bus->params.bandwidth -= m_rt->stream->params.rate *
 			m_rt->ch_count * m_rt->stream->params.bps;
+
+		/* Compute params */
+		if (bus->compute_params) {
+			ret = bus->compute_params(bus);
+			if (ret < 0) {
+				dev_err(bus->dev, "Compute params failed: %d",
+					ret);
+				return ret;
+			}
+		}
 
 		/* Program params */
 		ret = sdw_program_params(bus, false);

include/linux/soundwire/sdw.h

···
 
 struct sdw_stream_runtime *sdw_alloc_stream(const char *stream_name);
 void sdw_release_stream(struct sdw_stream_runtime *stream);
+
+int sdw_compute_params(struct sdw_bus *bus);
+
 int sdw_stream_add_master(struct sdw_bus *bus,
 		struct sdw_stream_config *stream_config,
 		struct sdw_port_config *port_config,