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Message-ID: <CH2PR12MB38957218E53584EFCC2496DDD7909@CH2PR12MB3895.namprd12.prod.outlook.com>
Date: Wed, 5 Apr 2023 13:57:11 +0000
From: Asmaa Mnebhi <asmaa@...dia.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Wolfram Sang <wsa@...nel.org>,
Khalil Blaiech <kblaiech@...dia.com>,
"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 1/1] i2c: mlxbf: Use readl_poll_timeout_atomic() for
polling
Reviewed-by: Asmaa Mnebhi <asmaa@...dia.com>
> Subject: [PATCH v2 1/1] i2c: mlxbf: Use readl_poll_timeout_atomic() for
> polling
>
> Convert the usage of an open-coded custom tight poll while loop with the
> provided readl_poll_timeout_atomic() macro.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
> v2: corrected comment (Asmaa)
> drivers/i2c/busses/i2c-mlxbf.c | 106 ++++++++-------------------------
> 1 file changed, 26 insertions(+), 80 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-mlxbf.c b/drivers/i2c/busses/i2c-mlxbf.c
> index 1810d5791b3d..d9d4b65cb276 100644
> --- a/drivers/i2c/busses/i2c-mlxbf.c
> +++ b/drivers/i2c/busses/i2c-mlxbf.c
> @@ -12,6 +12,7 @@
> #include <linux/interrupt.h>
> #include <linux/i2c.h>
> #include <linux/io.h>
> +#include <linux/iopoll.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/mutex.h>
> @@ -495,65 +496,6 @@ static u8 mlxbf_i2c_bus_count;
>
> static struct mutex mlxbf_i2c_bus_lock;
>
> -/*
> - * Function to poll a set of bits at a specific address; it checks whether
> - * the bits are equal to zero when eq_zero is set to 'true', and not equal
> - * to zero when eq_zero is set to 'false'.
> - * Note that the timeout is given in microseconds.
> - */
> -static u32 mlxbf_i2c_poll(void __iomem *io, u32 addr, u32 mask,
> - bool eq_zero, u32 timeout)
> -{
> - u32 bits;
> -
> - timeout = (timeout / MLXBF_I2C_POLL_FREQ_IN_USEC) + 1;
> -
> - do {
> - bits = readl(io + addr) & mask;
> - if (eq_zero ? bits == 0 : bits != 0)
> - return eq_zero ? 1 : bits;
> - udelay(MLXBF_I2C_POLL_FREQ_IN_USEC);
> - } while (timeout-- != 0);
> -
> - return 0;
> -}
> -
> -/*
> - * SW must make sure that the SMBus Master GW is idle before starting
> - * a transaction. Accordingly, this function polls the Master FSM stop
> - * bit; it returns false when the bit is asserted, true if not.
> - */
> -static bool mlxbf_i2c_smbus_master_wait_for_idle(struct mlxbf_i2c_priv
> *priv) -{
> - u32 mask = MLXBF_I2C_SMBUS_MASTER_FSM_STOP_MASK;
> - u32 addr = priv->chip->smbus_master_fsm_off;
> - u32 timeout = MLXBF_I2C_SMBUS_TIMEOUT;
> -
> - if (mlxbf_i2c_poll(priv->mst->io, addr, mask, true, timeout))
> - return true;
> -
> - return false;
> -}
> -
> -/*
> - * wait for the lock to be released before acquiring it.
> - */
> -static bool mlxbf_i2c_smbus_master_lock(struct mlxbf_i2c_priv *priv) -{
> - if (mlxbf_i2c_poll(priv->mst->io, MLXBF_I2C_SMBUS_MASTER_GW,
> - MLXBF_I2C_MASTER_LOCK_BIT, true,
> - MLXBF_I2C_SMBUS_LOCK_POLL_TIMEOUT))
> - return true;
> -
> - return false;
> -}
> -
> -static void mlxbf_i2c_smbus_master_unlock(struct mlxbf_i2c_priv *priv) -{
> - /* Clear the gw to clear the lock */
> - writel(0, priv->mst->io + MLXBF_I2C_SMBUS_MASTER_GW);
> -}
> -
> static bool mlxbf_i2c_smbus_transaction_success(u32 master_status,
> u32 cause_status)
> {
> @@ -583,6 +525,7 @@ static int mlxbf_i2c_smbus_check_status(struct
> mlxbf_i2c_priv *priv) {
> u32 master_status_bits;
> u32 cause_status_bits;
> + u32 bits;
>
> /*
> * GW busy bit is raised by the driver and cleared by the HW @@ -
> 591,9 +534,9 @@ static int mlxbf_i2c_smbus_check_status(struct
> mlxbf_i2c_priv *priv)
> * then read the cause and master status bits to determine if
> * errors occurred during the transaction.
> */
> - mlxbf_i2c_poll(priv->mst->io, MLXBF_I2C_SMBUS_MASTER_GW,
> - MLXBF_I2C_MASTER_BUSY_BIT, true,
> - MLXBF_I2C_SMBUS_TIMEOUT);
> + readl_poll_timeout_atomic(priv->mst->io +
> MLXBF_I2C_SMBUS_MASTER_GW,
> + bits, !(bits &
> MLXBF_I2C_MASTER_BUSY_BIT),
> + MLXBF_I2C_POLL_FREQ_IN_USEC,
> MLXBF_I2C_SMBUS_TIMEOUT);
>
> /* Read cause status bits. */
> cause_status_bits = readl(priv->mst_cause->io + @@ -740,7 +683,8
> @@ mlxbf_i2c_smbus_start_transaction(struct mlxbf_i2c_priv *priv,
> u8 read_en, write_en, block_en, pec_en;
> u8 slave, flags, addr;
> u8 *read_buf;
> - int ret = 0;
> + u32 bits;
> + int ret;
>
> if (request->operation_cnt > MLXBF_I2C_SMBUS_MAX_OP_CNT)
> return -EINVAL;
> @@ -760,11 +704,22 @@ mlxbf_i2c_smbus_start_transaction(struct
> mlxbf_i2c_priv *priv,
> * Try to acquire the smbus gw lock before any reads of the GW
> register since
> * a read sets the lock.
> */
> - if (WARN_ON(!mlxbf_i2c_smbus_master_lock(priv)))
> + ret = readl_poll_timeout_atomic(priv->mst->io +
> MLXBF_I2C_SMBUS_MASTER_GW,
> + bits, !(bits &
> MLXBF_I2C_MASTER_LOCK_BIT),
> + MLXBF_I2C_POLL_FREQ_IN_USEC,
> +
> MLXBF_I2C_SMBUS_LOCK_POLL_TIMEOUT);
> + if (WARN_ON(ret))
> return -EBUSY;
>
> - /* Check whether the HW is idle */
> - if (WARN_ON(!mlxbf_i2c_smbus_master_wait_for_idle(priv))) {
> + /*
> + * SW must make sure that the SMBus Master GW is idle before
> starting
> + * a transaction. Accordingly, this call polls the Master FSM stop bit;
> + * it returns -ETIMEDOUT when the bit is asserted, 0 if not.
> + */
> + ret = readl_poll_timeout_atomic(priv->mst->io + priv->chip-
> >smbus_master_fsm_off,
> + bits, !(bits &
> MLXBF_I2C_SMBUS_MASTER_FSM_STOP_MASK),
> + MLXBF_I2C_POLL_FREQ_IN_USEC,
> MLXBF_I2C_SMBUS_TIMEOUT);
> + if (WARN_ON(ret)) {
> ret = -EBUSY;
> goto out_unlock;
> }
> @@ -855,7 +810,8 @@ mlxbf_i2c_smbus_start_transaction(struct
> mlxbf_i2c_priv *priv,
> }
>
> out_unlock:
> - mlxbf_i2c_smbus_master_unlock(priv);
> + /* Clear the gw to clear the lock */
> + writel(0, priv->mst->io + MLXBF_I2C_SMBUS_MASTER_GW);
>
> return ret;
> }
> @@ -1835,18 +1791,6 @@ static bool mlxbf_i2c_has_coalesce(struct
> mlxbf_i2c_priv *priv, bool *read,
> return true;
> }
>
> -static bool mlxbf_i2c_slave_wait_for_idle(struct mlxbf_i2c_priv *priv,
> - u32 timeout)
> -{
> - u32 mask = MLXBF_I2C_CAUSE_S_GW_BUSY_FALL;
> - u32 addr = MLXBF_I2C_CAUSE_ARBITER;
> -
> - if (mlxbf_i2c_poll(priv->slv_cause->io, addr, mask, false, timeout))
> - return true;
> -
> - return false;
> -}
> -
> static struct i2c_client *mlxbf_i2c_get_slave_from_addr(
> struct mlxbf_i2c_priv *priv, u8 addr) { @@ -1949,7
> +1893,9 @@ static int mlxbf_i2c_irq_send(struct mlxbf_i2c_priv *priv, u8
> recv_bytes)
> * Wait until the transfer is completed; the driver will wait
> * until the GW is idle, a cause will rise on fall of GW busy.
> */
> - mlxbf_i2c_slave_wait_for_idle(priv, MLXBF_I2C_SMBUS_TIMEOUT);
> + readl_poll_timeout_atomic(priv->slv_cause->io +
> MLXBF_I2C_CAUSE_ARBITER,
> + data32, data32 &
> MLXBF_I2C_CAUSE_S_GW_BUSY_FALL,
> + MLXBF_I2C_POLL_FREQ_IN_USEC,
> MLXBF_I2C_SMBUS_TIMEOUT);
>
> clear_csr:
> /* Release the Slave GW. */
> --
> 2.40.0.1.gaa8946217a0b
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