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    SubjectRe: [alsa-devel] [PATCH v4 08/15] soundwire: Add Slave status handling helpers
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    On 12/1/17 3:56 AM, Vinod Koul wrote:
    > From: Sanyog Kale <sanyog.r.kale@intel.com>
    >
    > SoundWire Slaves report status to bus. Add helpers to handle
    > the status changes.
    >
    > Signed-off-by: Hardik T Shah <hardik.t.shah@intel.com>
    > Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
    > Signed-off-by: Vinod Koul <vinod.koul@intel.com>
    > ---
    > drivers/soundwire/bus.c | 202 ++++++++++++++++++++++++++++++++++++++++++
    > drivers/soundwire/bus.h | 14 +++
    > include/linux/soundwire/sdw.h | 1 +
    > 3 files changed, 217 insertions(+)
    >
    > diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
    > index 2f108f162905..09126ddd3cdd 100644
    > --- a/drivers/soundwire/bus.c
    > +++ b/drivers/soundwire/bus.c
    > @@ -372,6 +372,93 @@ int sdw_write(struct sdw_slave *slave, u32 addr, u8 value)
    > }
    > EXPORT_SYMBOL(sdw_write);
    >
    > +/*
    > + * SDW alert handling
    > + */
    > +
    > +/* called with bus_lock held */
    > +static struct sdw_slave *sdw_get_slave(struct sdw_bus *bus, int i)
    > +{
    > + struct sdw_slave *slave = NULL;
    > +
    > + list_for_each_entry(slave, &bus->slaves, node) {
    > + if (slave->dev_num == i)
    > + return slave;
    > + }
    > +
    > + return NULL;
    > +}
    > +
    > +static int sdw_compare_devid(struct sdw_slave *slave, struct sdw_slave_id id)
    > +{
    > +
    > + if ((slave->id.unique_id != id.unique_id) ||
    > + (slave->id.mfg_id != id.mfg_id) ||
    > + (slave->id.part_id != id.part_id) ||
    > + (slave->id.class_id != id.class_id))
    > + return -ENODEV;
    > +
    > + return 0;
    > +}
    > +
    > +/* called with bus_lock held */
    > +static int sdw_get_device_num(struct sdw_slave *slave)
    > +{
    > + int bit;
    > +
    > + bit = find_first_zero_bit(slave->bus->assigned, SDW_MAX_DEVICES);
    > + if (bit == SDW_MAX_DEVICES) {
    > + bit = -ENODEV;
    > + goto err;

    My brain is starting to fry but is this correct? Bit11 seems like a
    valid value. Should it be bit > 15 (assuming bit 12,13,14 are set to
    avoid using groups and master)?


    > + }
    > +
    > + /*
    > + * Do not update dev_num in Slave data structure here,
    > + * Update once program dev_num is successful
    > + */
    > + set_bit(bit, slave->bus->assigned);
    > +
    > +err:
    > + return bit;
    > +}
    > +
    > +static int sdw_assign_device_num(struct sdw_slave *slave)
    > +{
    > + int ret, dev_num;
    > +
    > + /* check first if device number is assigned, if so reuse that */
    > + if (!slave->dev_num) {
    > + mutex_lock(&slave->bus->bus_lock);
    > + dev_num = sdw_get_device_num(slave);
    > + mutex_unlock(&slave->bus->bus_lock);
    > + if (dev_num < 0) {
    > + dev_err(slave->bus->dev, "Get dev_num failed: %d",
    > + dev_num);
    > + return dev_num;
    > + }
    > + } else {
    > + dev_info(slave->bus->dev,
    > + "Slave already registered dev_num:%d",
    > + slave->dev_num);
    > +
    > + /* Clear the slave->dev_num to transfer message on device 0 */
    > + dev_num = slave->dev_num;
    > + slave->dev_num = 0;
    > +
    > + }
    > +
    > + ret = sdw_write(slave, SDW_SCP_DEVNUMBER, dev_num);
    > + if (ret < 0) {
    > + dev_err(&slave->dev, "Program device_num failed: %d", ret);
    > + return ret;
    > + }
    > +
    > + /* After xfer of msg, restore dev_num */
    > + slave->dev_num = dev_num;
    > +
    > + return 0;
    > +}
    > +
    > void sdw_extract_slave_id(struct sdw_bus *bus,
    > u64 addr, struct sdw_slave_id *id)
    > {
    > @@ -400,3 +487,118 @@ void sdw_extract_slave_id(struct sdw_bus *bus,
    > id->unique_id, id->sdw_version);
    >
    > }
    > +
    > +static int sdw_program_device_num(struct sdw_bus *bus)
    > +{
    > + u8 buf[SDW_NUM_DEV_ID_REGISTERS] = {0};
    > + struct sdw_slave *slave, *_s;
    > + struct sdw_slave_id id;
    > + struct sdw_msg msg;
    > + bool found = false;
    > + int count = 0, ret;
    > + u64 addr;
    > +
    > + /* No Slave, so use raw xfer api */
    > + ret = sdw_fill_msg(&msg, NULL, SDW_SCP_DEVID_0,
    > + SDW_NUM_DEV_ID_REGISTERS, 0, SDW_MSG_FLAG_READ, buf);
    > + if (ret < 0)
    > + return ret;
    > +
    > + do {
    > + ret = sdw_transfer(bus, NULL, &msg);
    > + if (ret == -ENODATA) { /* end of device id reads */
    > + ret = 0;
    > + break;
    > + }
    > + if (ret < 0) {
    > + dev_err(bus->dev, "DEVID read fail:%d\n", ret);
    > + break;
    > + }
    > +
    > + /*
    > + * Construct the addr and extract. Cast the higher shift
    > + * bits to avoid truncation due to size limit.
    > + */
    > + addr = buf[5] | (buf[4] << 8) | (buf[3] << 16) |
    > + (buf[2] << 24) | ((unsigned long long)buf[1] << 32) |
    > + ((unsigned long long)buf[0] << 40);
    > +
    > + sdw_extract_slave_id(bus, addr, &id);
    > +
    > + /* Now compare with entries */
    > + list_for_each_entry_safe(slave, _s, &bus->slaves, node) {
    > + if (sdw_compare_devid(slave, id) == 0) {
    > + found = true;
    > +
    > + /*
    > + * Assign a new dev_num to this Slave and
    > + * not mark it present. It will be marked
    > + * present after it reports ATTACHED on new
    > + * dev_num
    > + */
    > + ret = sdw_assign_device_num(slave);
    > + if (ret) {
    > + dev_err(slave->bus->dev,
    > + "Assign dev_num failed:%d",
    > + ret);
    > + return ret;
    > + }
    > +
    > + break;
    > + }
    > + }
    > +
    > + if (found == false) {
    > + /* TODO: Park this device in Group 13 */
    > + dev_err(bus->dev, "Slave Entry not found");
    > + }
    > +
    > + count++;
    > +
    > + } while (ret == 0 && count < (SDW_MAX_DEVICES * 2));

    explain that the last condition is intentional - this is not a bug -,
    some devices can drop off during enumeration and rejoin so might be
    counted twice.

    > +
    > + return ret;
    > +}
    > +
    > +static void sdw_modify_slave_status(struct sdw_slave *slave,
    > + enum sdw_slave_status status)
    > +{
    > + mutex_lock(&slave->bus->bus_lock);
    > + slave->status = status;
    > + mutex_unlock(&slave->bus->bus_lock);
    > +}
    > +
    > +static int sdw_initialize_slave(struct sdw_slave *slave)
    > +{
    > + struct sdw_slave_prop *prop = &slave->prop;
    > + int ret;
    > + u8 val;
    > +
    > + /* Set bus clash and parity interrupt mask */
    > + val = SDW_SCP_INT1_BUS_CLASH | SDW_SCP_INT1_PARITY;
    > +
    > + /* Enable SCP interrupts */
    > + ret = sdw_update(slave, SDW_SCP_INTMASK1, val, val);
    > + if (ret < 0) {
    > + dev_err(slave->bus->dev,
    > + "SDW_SCP_INTMASK1 write failed:%d", ret);
    > + return ret;
    > + }
    > +
    > + /* No need to continue if DP0 is not present */
    > + if (!slave->prop.dp0_prop)
    > + return 0;
    > +
    > + /* Enable DP0 interrupts */
    > + val = prop->dp0_prop->device_interrupts;
    > + val |= SDW_DP0_INT_PORT_READY | SDW_DP0_INT_BRA_FAILURE;
    > +
    > + ret = sdw_update(slave, SDW_DP0_INTMASK, val, val);
    > + if (ret < 0) {
    > + dev_err(slave->bus->dev,
    > + "SDW_DP0_INTMASK read failed:%d", ret);
    > + return val;
    > + }
    > +
    > + return 0;
    > +}
    > diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
    > index bde5f840ca96..b491e86f2c4c 100644
    > --- a/drivers/soundwire/bus.h
    > +++ b/drivers/soundwire/bus.h
    > @@ -53,4 +53,18 @@ int sdw_transfer_defer(struct sdw_bus *bus, struct sdw_slave *slave,
    > int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
    > u32 addr, size_t count, u16 dev_num, u8 flags, u8 *buf);
    >
    > +/* Read-Modify-Write Slave register */
    > +static inline int
    > +sdw_update(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
    > +{
    > + int tmp;
    > +
    > + tmp = sdw_read(slave, addr);
    > + if (tmp < 0)
    > + return tmp;
    > +
    > + tmp = (tmp & ~mask) | val;
    > + return sdw_write(slave, addr, tmp);
    > +}
    > +
    > #endif /* __SDW_BUS_H */
    > diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
    > index d3337b5b882b..09619d042909 100644
    > --- a/include/linux/soundwire/sdw.h
    > +++ b/include/linux/soundwire/sdw.h
    > @@ -15,6 +15,7 @@ struct sdw_slave;
    > /* SDW Enumeration Device Number */
    > #define SDW_ENUM_DEV_NUM 0
    >
    > +#define SDW_NUM_DEV_ID_REGISTERS 6
    > #define SDW_MAX_DEVICES 11
    >
    > /**
    >

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