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mtd: spi-nor: cadence-quadspi: Add support to enable loop-back clock circuit 

Cadence QSPI IP has a adapted loop-back circuit which can be enabled by
setting BYPASS field to 0 in READCAPTURE register. It enables use of
QSPI return clock to latch the data rather than the internal QSPI
reference clock. For high speed operations, adapted loop-back circuit
using QSPI return clock helps to increase data valid window.

Based on DT parameter cdns,rclk-en enable adapted loop-back circuit
for boards which do have QSPI return clock provided.
This patch also modifies cqspi_readdata_capture() function's bypass
parameter to bool to match how its used in the function.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>
This commit is contained in:
Vignesh R 2017-10-03 10:49:23 +05:30 committed by Cyrille Pitchen
parent 00df263560
commit e2580a4add
1 changed files with 6 additions and 2 deletions
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8
drivers/mtd/spi-nor/cadence-quadspi.c
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@ -78,6 +78,7 @@ struct cqspi_st {
bool is_decoded_cs;
u32 fifo_depth;
u32 fifo_width;
bool rclk_en;
u32 trigger_address;
u32 wr_delay;
struct cqspi_flash_pdata f_pdata[CQSPI_MAX_CHIPSELECT];
@ -788,7 +789,7 @@ static void cqspi_config_baudrate_div(struct cqspi_st *cqspi)
}
static void cqspi_readdata_capture(struct cqspi_st *cqspi,
const unsigned int bypass,
const bool bypass,
const unsigned int delay)
{
void __iomem *reg_base = cqspi->iobase;
@ -852,7 +853,8 @@ static void cqspi_configure(struct spi_nor *nor)
cqspi->sclk = sclk;
cqspi_config_baudrate_div(cqspi);
cqspi_delay(nor);
cqspi_readdata_capture(cqspi, 1, f_pdata->read_delay);
cqspi_readdata_capture(cqspi, !cqspi->rclk_en,
f_pdata->read_delay);
}
if (switch_cs || switch_ck)
@ -1049,6 +1051,8 @@ static int cqspi_of_get_pdata(struct platform_device *pdev)
return -ENXIO;
}
cqspi->rclk_en = of_property_read_bool(np, "cdns,rclk-en");
return 0;
}