[PATCH v7 01/34] i2c: tegra: Make tegra_i2c_flush_fifos() usable in atomic transfer

[Dmitry Osipenko]

The tegra_i2c_flush_fifos() shouldn't sleep in atomic transfer and jiffies
are not updating if interrupts are disabled. Let's switch to use iopoll
API helpers for register-polling. The iopoll API provides helpers for both
atomic and non-atomic cases.

Note that this patch doesn't fix any known problem because normally FIFO
is flushed at the time of starting a new transfer.

Reviewed-by: Michał Mirosław <mirq-li...@rere.qmqm.pl>
Signed-off-by: Dmitry Osipenko <dig...@gmail.com>
---
 drivers/i2c/busses/i2c-tegra.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 00d3e4d7a01e..ab88cdd70376 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -470,9 +470,9 @@ static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev)
 
 static int tegra_i2c_flush_fifos(struct tegra_i2c_dev *i2c_dev)
 {
-       unsigned long timeout = jiffies + HZ;
-       unsigned int offset;
-       u32 mask, val;
+       u32 mask, val, offset, reg_offset;
+       void __iomem *addr;
+       int err;
 
        if (i2c_dev->hw->has_mst_fifo) {
                mask = I2C_MST_FIFO_CONTROL_TX_FLUSH |
@@ -488,12 +488,19 @@ static int tegra_i2c_flush_fifos(struct tegra_i2c_dev 
*i2c_dev)
        val |= mask;
        i2c_writel(i2c_dev, val, offset);
 
-       while (i2c_readl(i2c_dev, offset) & mask) {
-               if (time_after(jiffies, timeout)) {
-                       dev_warn(i2c_dev->dev, "timeout waiting for fifo 
flush\n");
-                       return -ETIMEDOUT;
-               }
-               usleep_range(1000, 2000);
+       reg_offset = tegra_i2c_reg_addr(i2c_dev, offset);
+       addr = i2c_dev->base + reg_offset;
+
+       if (i2c_dev->is_curr_atomic_xfer)
+               err = readl_relaxed_poll_timeout_atomic(addr, val, !(val & 
mask),
+                                                       1000, 1000000);
+       else
+               err = readl_relaxed_poll_timeout(addr, val, !(val & mask),
+                                                1000, 1000000);
+
+       if (err) {
+               dev_err(i2c_dev->dev, "failed to flush FIFO\n");
+               return err;
        }
        return 0;
 }
-- 
2.27.0