[PATCH 5/6] soundwire: qcom: update register read/write routine

From: Srinivas Kandagatla
Date: Fri Jan 29 2021 - 12:44:24 EST

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.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
drivers/soundwire/qcom.c | 148 +++++++++++++++++++++++++--------------
1 file changed, 96 insertions(+), 52 deletions(-)

diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
index 83df15d83935..d61b204dc284 100644
--- a/drivers/soundwire/qcom.c
+++ b/drivers/soundwire/qcom.c
@@ -78,13 +78,15 @@
#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 MAX_FIFO_RD_FAIL_RETRY 3

struct qcom_swrm_port_config {
u8 si;
@@ -104,11 +106,13 @@ struct qcom_swrm_ctrl {
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 mutex io_lock;
struct clk *hclk;
u8 wr_cmd_id;
u8 rd_cmd_id;
@@ -122,6 +126,8 @@ 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];
@@ -200,75 +206,111 @@ 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 < 14)
+ 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;
+ int ret = 0;
+ u8 cmd_id = 0x0;
+
+ mutex_lock(&swrm->io_lock);
+ 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);
+ }

- spin_lock_irqsave(&ctrl->comp_lock, flags);
- ctrl->comp = &comp;
- spin_unlock_irqrestore(&ctrl->comp_lock, flags);
+ swrm->reg_write(swrm, SWRM_CMD_FIFO_WR_CMD, val);

- 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;
+ /* version 1.3 or less */
+ if (swrm->version_major == 1 && swrm->version_minor <= 3)
+ usleep_range(150, 155);

- ret = wait_for_completion_timeout(ctrl->comp,
- msecs_to_jiffies(TIMEOUT_MS));
+ 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, (2 * HZ/10));
+ if (!ret)
+ ret = SDW_CMD_IGNORED;
+ else
+ ret = SDW_CMD_OK;

- if (!ret) {
- ret = SDW_CMD_IGNORED;
- goto err;
} else {
ret = SDW_CMD_OK;
}
+ mutex_unlock(&swrm->io_lock);
+ 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 val;
+ u32 retry_attempt = 0;
+ u32 cmd_data;
+ int ret = SDW_CMD_OK;
+
+ mutex_lock(&swrm->io_lock);
+ 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);
+
+retry_read:
+
+ swrm->reg_read(swrm, SWRM_CMD_FIFO_RD_FIFO_ADDR, &cmd_data);
+ rval[0] = cmd_data & 0xFF;
+
+ if ((((cmd_data) & 0xF00) >> 8) != swrm->rcmd_id) {
+ if (retry_attempt < MAX_FIFO_RD_FAIL_RETRY) {
+ /* wait 500 us before retry on fifo read failure */
+ usleep_range(500, 505);
+ if (retry_attempt == (MAX_FIFO_RD_FAIL_RETRY - 1)) {
+ swrm->reg_write(swrm, SWRM_CMD_FIFO_CMD, 0x1);
+ swrm->reg_write(swrm, SWRM_CMD_FIFO_RD_CMD, val);
+ }
+ retry_attempt++;
+ goto retry_read;
+ } else {
+ 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);
+ ret = SDW_CMD_IGNORED;
+ }
}

-err:
- spin_lock_irqsave(&ctrl->comp_lock, flags);
- ctrl->comp = NULL;
- spin_unlock_irqrestore(&ctrl->comp_lock, flags);
+ mutex_unlock(&swrm->io_lock);

return ret;
}
@@ -949,6 +991,8 @@ static int qcom_swrm_probe(struct platform_device *pdev)
dev_set_drvdata(&pdev->dev, ctrl);
spin_lock_init(&ctrl->comp_lock);
mutex_init(&ctrl->port_lock);
+ mutex_init(&ctrl->io_lock);
+ init_completion(&ctrl->broadcast);
INIT_WORK(&ctrl->slave_work, qcom_swrm_slave_wq);

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