[PATCH v5 5/9] soundwire: qcom: update register read/write routine

Srinivas Kandagatla
2021-03-26T06:42:30Z

In the existing code every soundwire register read and register write
are kinda blocked. Each of these are using a special command id that
generates interrupt after it successfully finishes. This is really
overhead, limiting and not really necessary unless we are doing
something special.

We can simply read/write the fifo that should also give exactly
what we need! This will also allow to read/write registers in
interrupt context, which was not possible with the special
command approach.

With previous approach number of interrupts generated
after enumeration are around 130:
$ cat /proc/interrupts | grep soundwire
21: 130 0 0 0 0 0 0 0 GICv3 234 Edge soundwire

after this patch they are just 3 interrupts
$ cat /proc/interrupts | grep soundwire
21: 3 0 0 0 0 0 0 0 GICv3 234 Edge soundwire

This has significantly not only reduced interrupting CPU during enumeration
but also during streaming!

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
drivers/soundwire/qcom.c | 178 ++++++++++++++++++++++-----------------
1 file changed, 99 insertions(+), 79 deletions(-)

diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
index 2bcb4362f0e0..0cbd611fb8c6 100644
--- a/drivers/soundwire/qcom.c
+++ b/drivers/soundwire/qcom.c
@@ -38,11 +38,13 @@
#define SWRM_CMD_FIFO_WR_CMD 0x300
#define SWRM_CMD_FIFO_RD_CMD 0x304
#define SWRM_CMD_FIFO_CMD 0x308
+#define SWRM_CMD_FIFO_FLUSH 0x1
#define SWRM_CMD_FIFO_STATUS 0x30C
#define SWRM_CMD_FIFO_CFG_ADDR 0x314
#define SWRM_CONTINUE_EXEC_ON_CMD_IGNORE BIT(31)
#define SWRM_RD_WR_CMD_RETRIES 0x7
#define SWRM_CMD_FIFO_RD_FIFO_ADDR 0x318
+#define SWRM_RD_FIFO_CMD_ID_MASK GENMASK(11, 8)
#define SWRM_ENUMERATOR_CFG_ADDR 0x500
#define SWRM_MCP_FRAME_CTRL_BANK_ADDR(m) (0x101C + 0x40 * (m))
#define SWRM_MCP_FRAME_CTRL_BANK_COL_CTRL_BMSK GENMASK(2, 0)
@@ -78,13 +80,16 @@
#define SWRM_SPECIAL_CMD_ID 0xF
#define MAX_FREQ_NUM 1
#define TIMEOUT_MS (2 * HZ)
-#define QCOM_SWRM_MAX_RD_LEN 0xf
+#define QCOM_SWRM_MAX_RD_LEN 0x1
#define QCOM_SDW_MAX_PORTS 14
#define DEFAULT_CLK_FREQ 9600000
#define SWRM_MAX_DAIS 0xF
#define SWR_INVALID_PARAM 0xFF
#define SWR_HSTOP_MAX_VAL 0xF
#define SWR_HSTART_MIN_VAL 0x0
+#define SWR_BROADCAST_CMD_ID 0x0F
+#define SWR_MAX_CMD_ID 14
+#define MAX_FIFO_RD_RETRY 3

struct qcom_swrm_port_config {
u8 si;
@@ -103,10 +108,8 @@ struct qcom_swrm_ctrl {
struct device *dev;
struct regmap *regmap;
void __iomem *mmio;
- struct completion *comp;
+ struct completion broadcast;
struct work_struct slave_work;
- /* read/write lock */
- spinlock_t comp_lock;
/* Port alloc/free lock */
struct mutex port_lock;
struct clk *hclk;
@@ -120,6 +123,8 @@ struct qcom_swrm_ctrl {
int rows_index;
unsigned long dout_port_mask;
unsigned long din_port_mask;
+ u8 rcmd_id;
+ u8 wcmd_id;
struct qcom_swrm_port_config pconfig[QCOM_SDW_MAX_PORTS];
struct sdw_stream_runtime *sruntime[SWRM_MAX_DAIS];
enum sdw_slave_status status[SDW_MAX_DEVICES];
@@ -198,77 +203,105 @@ static int qcom_swrm_cpu_reg_write(struct qcom_swrm_ctrl *ctrl, int reg,
return SDW_CMD_OK;
}

-static int qcom_swrm_cmd_fifo_wr_cmd(struct qcom_swrm_ctrl *ctrl, u8 cmd_data,
- u8 dev_addr, u16 reg_addr)
+static u32 swrm_get_packed_reg_val(u8 *cmd_id, u8 cmd_data,
+ u8 dev_addr, u16 reg_addr)
{
- DECLARE_COMPLETION_ONSTACK(comp);
- unsigned long flags;
u32 val;
- int ret;
-
- spin_lock_irqsave(&ctrl->comp_lock, flags);
- ctrl->comp = &comp;
- spin_unlock_irqrestore(&ctrl->comp_lock, flags);
- val = SWRM_REG_VAL_PACK(cmd_data, dev_addr,
- SWRM_SPECIAL_CMD_ID, reg_addr);
- ret = ctrl->reg_write(ctrl, SWRM_CMD_FIFO_WR_CMD, val);
- if (ret)
- goto err;
-
- ret = wait_for_completion_timeout(ctrl->comp,
- msecs_to_jiffies(TIMEOUT_MS));
+ u8 id = *cmd_id;

- if (!ret)
- ret = SDW_CMD_IGNORED;
- else
- ret = SDW_CMD_OK;
-err:
- spin_lock_irqsave(&ctrl->comp_lock, flags);
- ctrl->comp = NULL;
- spin_unlock_irqrestore(&ctrl->comp_lock, flags);
+ if (id != SWR_BROADCAST_CMD_ID) {
+ if (id < SWR_MAX_CMD_ID)
+ id += 1;
+ else
+ id = 0;
+ *cmd_id = id;
+ }
+ val = SWRM_REG_VAL_PACK(cmd_data, dev_addr, id, reg_addr);

- return ret;
+ return val;
}

-static int qcom_swrm_cmd_fifo_rd_cmd(struct qcom_swrm_ctrl *ctrl,
- u8 dev_addr, u16 reg_addr,
- u32 len, u8 *rval)
+
+static int qcom_swrm_cmd_fifo_wr_cmd(struct qcom_swrm_ctrl *swrm, u8 cmd_data,
+ u8 dev_addr, u16 reg_addr)
{
- int i, ret;
- u32 val;
- DECLARE_COMPLETION_ONSTACK(comp);
- unsigned long flags;

- spin_lock_irqsave(&ctrl->comp_lock, flags);
- ctrl->comp = &comp;
- spin_unlock_irqrestore(&ctrl->comp_lock, flags);
+ u32 val;
+ int ret = 0;
+ u8 cmd_id = 0x0;

- val = SWRM_REG_VAL_PACK(len, dev_addr, SWRM_SPECIAL_CMD_ID, reg_addr);
- ret = ctrl->reg_write(ctrl, SWRM_CMD_FIFO_RD_CMD, val);
- if (ret)
- goto err;
+ if (dev_addr == SDW_BROADCAST_DEV_NUM) {
+ cmd_id = SWR_BROADCAST_CMD_ID;
+ val = swrm_get_packed_reg_val(&cmd_id, cmd_data,
+ dev_addr, reg_addr);
+ } else {
+ val = swrm_get_packed_reg_val(&swrm->wcmd_id, cmd_data,
+ dev_addr, reg_addr);
+ }

- ret = wait_for_completion_timeout(ctrl->comp,
- msecs_to_jiffies(TIMEOUT_MS));
+ swrm->reg_write(swrm, SWRM_CMD_FIFO_WR_CMD, val);
+
+ /* version 1.3 or less */
+ if (swrm->version <= 0x01030000)
+ usleep_range(150, 155);
+
+ if (cmd_id == SWR_BROADCAST_CMD_ID) {
+ /*
+ * sleep for 10ms for MSM soundwire variant to allow broadcast
+ * command to complete.
+ */
+ ret = wait_for_completion_timeout(&swrm->broadcast,
+ msecs_to_jiffies(TIMEOUT_MS));
+ if (!ret)
+ ret = SDW_CMD_IGNORED;
+ else
+ ret = SDW_CMD_OK;

- if (!ret) {
- ret = SDW_CMD_IGNORED;
- goto err;
} else {
ret = SDW_CMD_OK;
}
+ return ret;
+}

- for (i = 0; i < len; i++) {
- ctrl->reg_read(ctrl, SWRM_CMD_FIFO_RD_FIFO_ADDR, &val);
- rval[i] = val & 0xFF;
- }
+static int qcom_swrm_cmd_fifo_rd_cmd(struct qcom_swrm_ctrl *swrm,
+ u8 dev_addr, u16 reg_addr,
+ u32 len, u8 *rval)
+{
+ u32 cmd_data, cmd_id, val, retry_attempt = 0;
+
+ val = swrm_get_packed_reg_val(&swrm->rcmd_id, len, dev_addr, reg_addr);
+
+ /* wait for FIFO RD to complete to avoid overflow */
+ usleep_range(100, 105);
+ swrm->reg_write(swrm, SWRM_CMD_FIFO_RD_CMD, val);
+ /* wait for FIFO RD CMD complete to avoid overflow */
+ usleep_range(250, 255);
+
+ do {
+ swrm->reg_read(swrm, SWRM_CMD_FIFO_RD_FIFO_ADDR, &cmd_data);
+ rval[0] = cmd_data & 0xFF;
+ cmd_id = FIELD_GET(SWRM_RD_FIFO_CMD_ID_MASK, cmd_data);
+
+ if (cmd_id != swrm->rcmd_id) {
+ if (retry_attempt < (MAX_FIFO_RD_RETRY - 1)) {
+ /* wait 500 us before retry on fifo read failure */
+ usleep_range(500, 505);
+ swrm->reg_write(swrm, SWRM_CMD_FIFO_CMD,
+ SWRM_CMD_FIFO_FLUSH);
+ swrm->reg_write(swrm, SWRM_CMD_FIFO_RD_CMD, val);
+ }
+ retry_attempt++;
+ } else {
+ return SDW_CMD_OK;
+ }

-err:
- spin_lock_irqsave(&ctrl->comp_lock, flags);
- ctrl->comp = NULL;
- spin_unlock_irqrestore(&ctrl->comp_lock, flags);
+ } while (retry_attempt < MAX_FIFO_RD_RETRY);

- return ret;
+ dev_err(swrm->dev, "failed to read fifo: reg: 0x%x, rcmd_id: 0x%x,\
+ dev_num: 0x%x, cmd_data: 0x%x\n",
+ reg_addr, swrm->rcmd_id, dev_addr, cmd_data);
+
+ return SDW_CMD_IGNORED;
}

static void qcom_swrm_get_device_status(struct qcom_swrm_ctrl *ctrl)
@@ -291,7 +324,6 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
{
struct qcom_swrm_ctrl *ctrl = dev_id;
u32 sts, value;
- unsigned long flags;

ctrl->reg_read(ctrl, SWRM_INTERRUPT_STATUS, &sts);

@@ -304,8 +336,10 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
}

if ((sts & SWRM_INTERRUPT_STATUS_NEW_SLAVE_ATTACHED) ||
- sts & SWRM_INTERRUPT_STATUS_CHANGE_ENUM_SLAVE_STATUS)
- schedule_work(&ctrl->slave_work);
+ sts & SWRM_INTERRUPT_STATUS_CHANGE_ENUM_SLAVE_STATUS) {
+ qcom_swrm_get_device_status(ctrl);
+ sdw_handle_slave_status(&ctrl->bus, ctrl->status);
+ }

/**
* clear the interrupt before complete() is called, as complete can
@@ -314,15 +348,12 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
*/
ctrl->reg_write(ctrl, SWRM_INTERRUPT_CLEAR, sts);

- if (sts & SWRM_INTERRUPT_STATUS_SPECIAL_CMD_ID_FINISHED) {
- spin_lock_irqsave(&ctrl->comp_lock, flags);
- if (ctrl->comp)
- complete(ctrl->comp);
- spin_unlock_irqrestore(&ctrl->comp_lock, flags);
- }
+ if (sts & SWRM_INTERRUPT_STATUS_SPECIAL_CMD_ID_FINISHED)
+ complete(&ctrl->broadcast);

return IRQ_HANDLED;
}
+
static int qcom_swrm_init(struct qcom_swrm_ctrl *ctrl)
{
u32 val;
@@ -570,16 +601,6 @@ static u32 qcom_swrm_freq_tbl[MAX_FREQ_NUM] = {
DEFAULT_CLK_FREQ,
};

-static void qcom_swrm_slave_wq(struct work_struct *work)
-{
- struct qcom_swrm_ctrl *ctrl =
- container_of(work, struct qcom_swrm_ctrl, slave_work);
-
- qcom_swrm_get_device_status(ctrl);
- sdw_handle_slave_status(&ctrl->bus, ctrl->status);
-}
-
-
static void qcom_swrm_stream_free_ports(struct qcom_swrm_ctrl *ctrl,
struct sdw_stream_runtime *stream)
{
@@ -947,9 +968,8 @@ static int qcom_swrm_probe(struct platform_device *pdev)

ctrl->dev = dev;
dev_set_drvdata(&pdev->dev, ctrl);
- spin_lock_init(&ctrl->comp_lock);
mutex_init(&ctrl->port_lock);
- INIT_WORK(&ctrl->slave_work, qcom_swrm_slave_wq);
+ init_completion(&ctrl->broadcast);

ctrl->bus.ops = &qcom_swrm_ops;
ctrl->bus.port_ops = &qcom_swrm_port_ops;
--
2.21.0