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spi: bcm-qspi: Use fastbr setting to allow faster MSPI speeds 

Setting MSPI_SPCR3.fastbr=1 allows using clock divider (SPBR) values of
1-7, while the default value prohibits these values and requires a minimum
clock divider value of 8.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Link: https://lore.kernel.org/r/20200420190853.45614-8-kdasu.kdev@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Kamal Dasu 2020-04-20 15:08:51 -04:00 committed by Mark Brown
parent 3a01f04d74
commit d9576ae5dc
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GPG Key ID: 24D68B725D5487D0
1 changed files with 33 additions and 3 deletions
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36
drivers/spi/spi-bcm-qspi.c
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@ -107,13 +107,15 @@
#define MSPI_SPCR2_SPE BIT(6)
#define MSPI_SPCR2_CONT_AFTER_CMD BIT(7)
#define MSPI_SPCR3_FASTBR BIT(0)
#define MSPI_SPCR3_FASTDT BIT(1)
#define MSPI_MSPI_STATUS_SPIF BIT(0)
#define INTR_BASE_BIT_SHIFT 0x02
#define INTR_COUNT 0x07
#define NUM_CHIPSELECT 4
#define QSPI_SPBR_MIN 8U
#define QSPI_SPBR_MAX 255U
#define OPCODE_DIOR 0xBB
@ -227,6 +229,25 @@ static inline bool has_bspi(struct bcm_qspi *qspi)
return qspi->bspi_mode;
}
/* hardware supports spcr3 and fast baud-rate */
static inline bool bcm_qspi_has_fastbr(struct bcm_qspi *qspi)
{
if (!has_bspi(qspi) &&
((qspi->mspi_maj_rev >= 1) &&
(qspi->mspi_min_rev >= 5)))
return true;
return false;
}
static inline int bcm_qspi_spbr_min(struct bcm_qspi *qspi)
{
if (bcm_qspi_has_fastbr(qspi))
return 1;
else
return 8;
}
/* Read qspi controller register*/
static inline u32 bcm_qspi_read(struct bcm_qspi *qspi, enum base_type type,
unsigned int offset)
@ -534,7 +555,7 @@ static void bcm_qspi_hw_set_parms(struct bcm_qspi *qspi,
if (xp->speed_hz)
spbr = qspi->base_clk / (2 * xp->speed_hz);
spcr = clamp_val(spbr, QSPI_SPBR_MIN, QSPI_SPBR_MAX);
spcr = clamp_val(spbr, bcm_qspi_spbr_min(qspi), QSPI_SPBR_MAX);
bcm_qspi_write(qspi, MSPI, MSPI_SPCR0_LSB, spcr);
spcr = MSPI_MASTER_BIT;
@ -544,6 +565,14 @@ static void bcm_qspi_hw_set_parms(struct bcm_qspi *qspi,
spcr |= xp->mode & 3;
bcm_qspi_write(qspi, MSPI, MSPI_SPCR0_MSB, spcr);
if (bcm_qspi_has_fastbr(qspi)) {
spcr = 0;
/* enable fastbr */
spcr |= MSPI_SPCR3_FASTBR;
bcm_qspi_write(qspi, MSPI, MSPI_SPCR3, spcr);
}
qspi->last_parms = *xp;
}
@ -1385,7 +1414,6 @@ int bcm_qspi_probe(struct platform_device *pdev,
}
qspi->base_clk = clk_get_rate(qspi->clk);
qspi->max_speed_hz = qspi->base_clk / (QSPI_SPBR_MIN * 2);
if (data->has_mspi_rev) {
rev = bcm_qspi_read(qspi, MSPI, MSPI_REV);
@ -1397,6 +1425,8 @@ int bcm_qspi_probe(struct platform_device *pdev,
qspi->mspi_maj_rev = (rev >> 4) & 0xf;
qspi->mspi_min_rev = rev & 0xf;
qspi->max_speed_hz = qspi->base_clk / (bcm_qspi_spbr_min(qspi) * 2);
bcm_qspi_hw_init(qspi);
init_completion(&qspi->mspi_done);
init_completion(&qspi->bspi_done);