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Subject[RFC PATCH 25/40] soundwire: intel: use BIOS information to set clock dividers
Date
The BIOS provides an Intel-specific property, let's use it to avoid
hard-coded clock dividers.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
drivers/soundwire/cadence_master.c | 26 ++++++++++++++++++++++----
drivers/soundwire/intel.c | 26 ++++++++++++++++++++++++++
include/linux/soundwire/sdw.h | 2 ++
3 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index d84344e29f71..10ebcef2e84e 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -173,8 +173,6 @@
#define CDNS_PDI_CONFIG_PORT GENMASK(4, 0)

/* Driver defaults */
-
-#define CDNS_DEFAULT_CLK_DIVIDER 0
#define CDNS_DEFAULT_SSP_INTERVAL 0x18
#define CDNS_TX_TIMEOUT 2000

@@ -973,7 +971,10 @@ static u32 cdns_set_default_frame_shape(int n_rows, int n_cols)
*/
int sdw_cdns_init(struct sdw_cdns *cdns)
{
+ struct sdw_bus *bus = &cdns->bus;
+ struct sdw_master_prop *prop = &bus->prop;
u32 val;
+ int divider;
int ret;

/* Exit clock stop */
@@ -985,9 +986,17 @@ int sdw_cdns_init(struct sdw_cdns *cdns)
}

/* Set clock divider */
+ divider = (prop->mclk_freq / prop->max_clk_freq) - 1;
val = cdns_readl(cdns, CDNS_MCP_CLK_CTRL0);
- val |= CDNS_DEFAULT_CLK_DIVIDER;
+ val |= divider;
cdns_writel(cdns, CDNS_MCP_CLK_CTRL0, val);
+ cdns_writel(cdns, CDNS_MCP_CLK_CTRL1, val);
+
+ pr_err("plb: mclk %d max_freq %d divider %d register %x\n",
+ prop->mclk_freq,
+ prop->max_clk_freq,
+ divider,
+ val);

/* Set the default frame shape */
val = cdns_set_default_frame_shape(prop->default_row,
@@ -1035,6 +1044,7 @@ EXPORT_SYMBOL(sdw_cdns_init);

int cdns_bus_conf(struct sdw_bus *bus, struct sdw_bus_params *params)
{
+ struct sdw_master_prop *prop = &bus->prop;
struct sdw_cdns *cdns = bus_to_cdns(bus);
int mcp_clkctrl_off, mcp_clkctrl;
int divider;
@@ -1044,7 +1054,9 @@ int cdns_bus_conf(struct sdw_bus *bus, struct sdw_bus_params *params)
return -EINVAL;
}

- divider = (params->max_dr_freq / params->curr_dr_freq) - 1;
+ divider = prop->mclk_freq * SDW_DOUBLE_RATE_FACTOR /
+ params->curr_dr_freq;
+ divider--; /* divider is 1/(N+1) */

if (params->next_bank)
mcp_clkctrl_off = CDNS_MCP_CLK_CTRL1;
@@ -1055,6 +1067,12 @@ int cdns_bus_conf(struct sdw_bus *bus, struct sdw_bus_params *params)
mcp_clkctrl |= divider;
cdns_writel(cdns, mcp_clkctrl_off, mcp_clkctrl);

+ pr_err("plb: mclk * 2 %d curr_dr_freq %d divider %d register %x\n",
+ prop->mclk_freq * SDW_DOUBLE_RATE_FACTOR,
+ params->curr_dr_freq,
+ divider,
+ mcp_clkctrl);
+
return 0;
}
EXPORT_SYMBOL(cdns_bus_conf);
diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index c718c9c67a37..796ac2bc8cea 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -917,11 +917,37 @@ static int intel_register_dai(struct sdw_intel *sdw)
dais, num_dai);
}

+static int sdw_master_read_intel_prop(struct sdw_bus *bus)
+{
+ struct sdw_master_prop *prop = &bus->prop;
+ struct fwnode_handle *link;
+ char name[32];
+ int nval, i;
+
+ /* Find master handle */
+ snprintf(name, sizeof(name),
+ "mipi-sdw-link-%d-subproperties", bus->link_id);
+
+ link = device_get_named_child_node(bus->dev, name);
+ if (!link) {
+ dev_err(bus->dev, "Master node %s not found\n", name);
+ return -EIO;
+ }
+
+ fwnode_property_read_u32(link,
+ "intel-sdw-ip-clock",
+ &prop->mclk_freq);
+ return 0;
+}
+
static int intel_prop_read(struct sdw_bus *bus)
{
/* Initialize with default handler to read all DisCo properties */
sdw_master_read_prop(bus);

+ /* read Intel-specific properties */
+ sdw_master_read_intel_prop(bus);
+
return 0;
}

diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 31d1e8acf25b..b6acc436ac80 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -379,6 +379,7 @@ struct sdw_slave_prop {
* @dynamic_frame: Dynamic frame shape supported
* @err_threshold: Number of times that software may retry sending a single
* command
+ * @mclk_freq: clock reference passed to SoundWire Master, in Hz.
*/
struct sdw_master_prop {
u32 revision;
@@ -393,6 +394,7 @@ struct sdw_master_prop {
u32 default_col;
bool dynamic_frame;
u32 err_threshold;
+ u32 mclk_freq;
};

int sdw_master_read_prop(struct sdw_bus *bus);
--
2.20.1
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