[RFC PATCH 25/40] soundwire: intel: use BIOS information to set clock dividers

[Pierre-Louis Bossart]

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.boss...@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