From 2e829ccc2779d4ea47050a2f41e7531a247a46e5 Mon Sep 17 00:00:00 2001 From: Hans Hu Date: Mon, 8 Apr 2024 10:54:46 +0800 Subject: [PATCH] i2c: wmt: fix a bug when thread blocked During each byte access, the host performs clock stretching. To reduce the host performs clock stretching, move most of the per-msg processing to the interrupt context. Suggested-by: Wolfram Sang Reviewed-by: Wolfram Sang Signed-off-by: Hans Hu Signed-off-by: Andi Shyti --- drivers/i2c/busses/i2c-viai2c-common.c | 145 +++++++++++++------------ drivers/i2c/busses/i2c-viai2c-common.h | 6 +- 2 files changed, 80 insertions(+), 71 deletions(-) diff --git a/drivers/i2c/busses/i2c-viai2c-common.c b/drivers/i2c/busses/i2c-viai2c-common.c index 59901c53ad48..1b39cf4f0d6c 100644 --- a/drivers/i2c/busses/i2c-viai2c-common.c +++ b/drivers/i2c/busses/i2c-viai2c-common.c @@ -18,37 +18,18 @@ int viai2c_wait_bus_not_busy(struct viai2c *i2c) return 0; } -int viai2c_check_status(struct viai2c *i2c) -{ - int ret = 0; - unsigned long time_left; - - time_left = wait_for_completion_timeout(&i2c->complete, - msecs_to_jiffies(500)); - if (!time_left) - return -ETIMEDOUT; - - if (i2c->cmd_status & VIAI2C_ISR_NACK_ADDR) - ret = -EIO; - - if (i2c->cmd_status & VIAI2C_ISR_SCL_TIMEOUT) - ret = -ETIMEDOUT; - - return ret; -} - static int viai2c_write(struct viai2c *i2c, struct i2c_msg *pmsg, int last) { u16 val, tcr_val = i2c->tcr; - int ret; - int xfer_len = 0; + + i2c->last = last; if (pmsg->len == 0) { /* * We still need to run through the while (..) once, so * start at -1 and break out early from the loop */ - xfer_len = -1; + i2c->xfered_len = -1; writew(0, i2c->base + VIAI2C_REG_CDR); } else { writew(pmsg->buf[0] & 0xFF, i2c->base + VIAI2C_REG_CDR); @@ -73,42 +54,15 @@ static int viai2c_write(struct viai2c *i2c, struct i2c_msg *pmsg, int last) writew(val, i2c->base + VIAI2C_REG_CR); } - while (xfer_len < pmsg->len) { - ret = viai2c_check_status(i2c); - if (ret) - return ret; + if (!wait_for_completion_timeout(&i2c->complete, VIAI2C_TIMEOUT)) + return -ETIMEDOUT; - xfer_len++; - - val = readw(i2c->base + VIAI2C_REG_CSR); - if (val & VIAI2C_CSR_RCV_NOT_ACK) { - dev_dbg(i2c->dev, "write RCV NACK error\n"); - return -EIO; - } - - if (pmsg->len == 0) { - val = VIAI2C_CR_TX_END | VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE; - writew(val, i2c->base + VIAI2C_REG_CR); - break; - } - - if (xfer_len == pmsg->len) { - if (last != 1) - writew(VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR); - } else { - writew(pmsg->buf[xfer_len] & 0xFF, i2c->base + VIAI2C_REG_CDR); - writew(VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR); - } - } - - return 0; + return i2c->ret; } static int viai2c_read(struct viai2c *i2c, struct i2c_msg *pmsg) { u16 val, tcr_val = i2c->tcr; - int ret; - u32 xfer_len = 0; val = readw(i2c->base + VIAI2C_REG_CR); val &= ~(VIAI2C_CR_TX_END | VIAI2C_CR_RX_END); @@ -133,21 +87,10 @@ static int viai2c_read(struct viai2c *i2c, struct i2c_msg *pmsg) writew(val, i2c->base + VIAI2C_REG_CR); } - while (xfer_len < pmsg->len) { - ret = viai2c_check_status(i2c); - if (ret) - return ret; + if (!wait_for_completion_timeout(&i2c->complete, VIAI2C_TIMEOUT)) + return -ETIMEDOUT; - pmsg->buf[xfer_len] = readw(i2c->base + VIAI2C_REG_CDR) >> 8; - xfer_len++; - - val = readw(i2c->base + VIAI2C_REG_CR) | VIAI2C_CR_CPU_RDY; - if (xfer_len == pmsg->len - 1) - val |= VIAI2C_CR_RX_END; - writew(val, i2c->base + VIAI2C_REG_CR); - } - - return 0; + return i2c->ret; } int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) @@ -165,6 +108,9 @@ int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) return ret; } + i2c->msg = pmsg; + i2c->xfered_len = 0; + if (pmsg->flags & I2C_M_RD) ret = viai2c_read(i2c, pmsg); else @@ -174,15 +120,76 @@ int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) return (ret < 0) ? ret : i; } +/* + * Main process of the byte mode xfer + * + * Return value indicates whether the transfer is complete + * 1: all the data has been successfully transferred + * 0: there is still data that needs to be transferred + * -EIO: error occurred + */ +static int viai2c_irq_xfer(struct viai2c *i2c) +{ + u16 val; + struct i2c_msg *msg = i2c->msg; + u8 read = msg->flags & I2C_M_RD; + void __iomem *base = i2c->base; + + if (read) { + msg->buf[i2c->xfered_len] = readw(base + VIAI2C_REG_CDR) >> 8; + + val = readw(base + VIAI2C_REG_CR) | VIAI2C_CR_CPU_RDY; + if (i2c->xfered_len == msg->len - 2) + val |= VIAI2C_CR_RX_END; + writew(val, base + VIAI2C_REG_CR); + } else { + val = readw(base + VIAI2C_REG_CSR); + if (val & VIAI2C_CSR_RCV_NOT_ACK) + return -EIO; + + /* I2C_SMBUS_QUICK */ + if (msg->len == 0) { + val = VIAI2C_CR_TX_END | VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE; + writew(val, base + VIAI2C_REG_CR); + return 1; + } + + if ((i2c->xfered_len + 1) == msg->len) { + if (!i2c->last) + writew(VIAI2C_CR_ENABLE, base + VIAI2C_REG_CR); + } else { + writew(msg->buf[i2c->xfered_len + 1] & 0xFF, base + VIAI2C_REG_CDR); + writew(VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE, base + VIAI2C_REG_CR); + } + } + + i2c->xfered_len++; + + return i2c->xfered_len == msg->len; +} + static irqreturn_t viai2c_isr(int irq, void *data) { struct viai2c *i2c = data; + u8 status; /* save the status and write-clear it */ - i2c->cmd_status = readw(i2c->base + VIAI2C_REG_ISR); - writew(i2c->cmd_status, i2c->base + VIAI2C_REG_ISR); + status = readw(i2c->base + VIAI2C_REG_ISR); + writew(status, i2c->base + VIAI2C_REG_ISR); - complete(&i2c->complete); + i2c->ret = 0; + if (status & VIAI2C_ISR_NACK_ADDR) + i2c->ret = -EIO; + + if (status & VIAI2C_ISR_SCL_TIMEOUT) + i2c->ret = -ETIMEDOUT; + + if (!i2c->ret) + i2c->ret = viai2c_irq_xfer(i2c); + + /* All the data has been successfully transferred or error occurred */ + if (i2c->ret) + complete(&i2c->complete); return IRQ_HANDLED; } diff --git a/drivers/i2c/busses/i2c-viai2c-common.h b/drivers/i2c/busses/i2c-viai2c-common.h index 28799e7e97f0..c92e054ac7e7 100644 --- a/drivers/i2c/busses/i2c-viai2c-common.h +++ b/drivers/i2c/busses/i2c-viai2c-common.h @@ -58,11 +58,13 @@ struct viai2c { struct clk *clk; u16 tcr; int irq; - u16 cmd_status; + u16 xfered_len; + struct i2c_msg *msg; + int ret; + bool last; }; int viai2c_wait_bus_not_busy(struct viai2c *i2c); -int viai2c_check_status(struct viai2c *i2c); int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num); int viai2c_init(struct platform_device *pdev, struct viai2c **pi2c);