spi: amd: Use iopoll for busy waiting

Instead of implementing a custom IO busy wait function, just use
readl_poll_timeout().
Signed-off-by: André Almeida <andrealmeid@collabora.com>
Link: https://lore.kernel.org/r/20220211143155.75513-2-andrealmeid@collabora.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-amd.c

@@ -12,6 +12,7 @@
 #include <linux/platform_device.h>
 #include <linux/delay.h>
 #include <linux/spi/spi.h>
+#include <linux/iopoll.h>
 
 #define AMD_SPI_CTRL0_REG	0x00
 #define AMD_SPI_EXEC_CMD	BIT(16)
@@ -103,16 +104,10 @@ static inline void amd_spi_set_tx_count(struct amd_spi *amd_spi, u8 tx_count)
 
 static int amd_spi_busy_wait(struct amd_spi *amd_spi)
 {
-	int timeout = 100000;
+	u32 val;
 
-	/* poll for SPI bus to become idle */
-	while (amd_spi_readreg32(amd_spi, AMD_SPI_CTRL0_REG) & AMD_SPI_BUSY) {
-		usleep_range(10, 20);
-		if (timeout-- < 0)
-			return -ETIMEDOUT;
-	}
-
-	return 0;
+	return readl_poll_timeout(amd_spi->io_remap_addr + AMD_SPI_CTRL0_REG,
+				  val, !(val & AMD_SPI_BUSY), 20, 2000000);
 }
 
 static int amd_spi_execute_opcode(struct amd_spi *amd_spi)