| Message ID | 1608236927-28701-7-git-send-email-skomatineni@nvidia.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add Tegra Quad SPI driver | expand |
On Thu, 17 Dec 2020 12:28:44 -0800 Sowjanya Komatineni <skomatineni@nvidia.com> wrote: > Tegra Quad SPI controller hardware supports sending dummy bytes based > on programmed dummy clock cycles after the actual transfer bytes. > > This patch adds this support of hardware dummy bytes transfer and > skips transfer of dummy bytes from the software. > > For dummy cycles more than Tegra Quad SPI hardware maximum dummy > cycles limit, driver transfers dummy bytes from the software. > > Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com> > --- > drivers/spi/spi-tegra210-quad.c | 41 ++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 40 insertions(+), 1 deletion(-) > > diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c > index e7bee8d..695a296 100644 > --- a/drivers/spi/spi-tegra210-quad.c > +++ b/drivers/spi/spi-tegra210-quad.c > @@ -117,6 +117,7 @@ > > #define QSPI_MISC_REG 0x194 > #define QSPI_NUM_DUMMY_CYCLE(x) (((x) & 0xff) << 0) > +#define QSPI_DUMMY_CYCLES_MAX 0xff > > #define DATA_DIR_TX BIT(0) > #define DATA_DIR_RX BIT(1) > @@ -170,6 +171,7 @@ struct tegra_qspi { > u32 def_command2_reg; > u32 spi_cs_timing1; > u32 spi_cs_timing2; > + u8 dummy_cycles; > > struct completion xfer_completion; > struct spi_transfer *curr_xfer; > @@ -856,6 +858,8 @@ static int tegra_qspi_start_transfer_one(struct spi_device *spi, > > tqspi->command1_reg = command1; > > + tegra_qspi_writel(tqspi, QSPI_NUM_DUMMY_CYCLE(tqspi->dummy_cycles), QSPI_MISC_REG); > + > ret = tegra_qspi_flush_fifos(tqspi, false); > if (ret < 0) > return ret; > @@ -974,7 +978,8 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi > { > struct tegra_qspi *tqspi = spi_master_get_devdata(master); > struct spi_device *spi = msg->spi; > - struct spi_transfer *xfer; > + struct spi_transfer *xfer, *next_xfer; next_after should be declared where it's actually used. > + bool use_hw_dummy_cycles = false; I don't think you need this variable (see below). > bool is_first_msg = true; > int ret; > > @@ -984,8 +989,42 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi > tqspi->rx_status = 0; > > list_for_each_entry(xfer, &msg->transfers, transfer_list) { > + u8 dummy_cycles = 0; Should be declared where it's actually used, and you don't want it to be a u8 since you're checking that the result does not exceed 255 which will always be true with a u8. > u32 cmd1; > > + /* > + * Skip dummy bytes transfer if they are transferred by the hardware along > + * with previous transfer. > + */ > + if (xfer->dummy_data && use_hw_dummy_cycles) { > + msg->actual_length += xfer->len; > + continue; > + } > + > + /* > + * Tegra QSPI hardware supports dummy bytes transfer after actual transfer > + * bytes based on programmed dummy clock cycles in the QSPI_MISC register. > + * So, check if the next transfer is dummy data transfer and program dummy > + * clock cycles along with the current transfer. > + */ > + if (!list_is_last(&xfer->transfer_list, &msg->transfers)) { > + next_xfer = list_next_entry(xfer, transfer_list); > + if (next_xfer && next_xfer->dummy_data) { > + dummy_cycles = next_xfer->len * 8 / next_xfer->tx_nbits; > + use_hw_dummy_cycles = true; > + /* > + * Use software dummy bytes transfer if dummy cycles exceeds > + * Tegra QSPI hardware maximum dummy cycles limit. > + */ > + if (dummy_cycles > QSPI_DUMMY_CYCLES_MAX) { > + use_hw_dummy_cycles = false; > + dummy_cycles = 0; > + } > + } > + } > + > + tqspi->dummy_cycles = dummy_cycles; > + This can be simplified: /* * Skip dummy bytes transfer if they were issued with the * previous transfer. */ if (tqspi->dummy_cycles) { WARN_ON(!xfer->dummy_data); tqspi->dummy_cycles = 0; } /* * Tegra QSPI hardware supports dummy bytes transfer after actual * transfer bytes based on programmed dummy clock cycles in the * QSPI_MISC register. So, check if the next transfer is dummy * data transfer and program dummy clock cycles along with the * current transfer. */ if (!list_is_last(&xfer->transfer_list, &msg->transfers)) { struct spi_transfer *next_xfer; next_xfer = list_next_entry(xfer, transfer_list); if (next_xfer->dummy_data) { u32 dummy_cycles = next_xfer->len * 8 / next_xfer->tx_nbits; if (dummy_cycles <= QSPI_DUMMY_CYCLES_MAX) tqspi->dummy_cycles = dummy_cycles; } } > reinit_completion(&tqspi->xfer_completion); > > cmd1 = tegra_qspi_setup_transfer_one(spi, xfer, is_first_msg);
diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c index e7bee8d..695a296 100644 --- a/drivers/spi/spi-tegra210-quad.c +++ b/drivers/spi/spi-tegra210-quad.c @@ -117,6 +117,7 @@ #define QSPI_MISC_REG 0x194 #define QSPI_NUM_DUMMY_CYCLE(x) (((x) & 0xff) << 0) +#define QSPI_DUMMY_CYCLES_MAX 0xff #define DATA_DIR_TX BIT(0) #define DATA_DIR_RX BIT(1) @@ -170,6 +171,7 @@ struct tegra_qspi { u32 def_command2_reg; u32 spi_cs_timing1; u32 spi_cs_timing2; + u8 dummy_cycles; struct completion xfer_completion; struct spi_transfer *curr_xfer; @@ -856,6 +858,8 @@ static int tegra_qspi_start_transfer_one(struct spi_device *spi, tqspi->command1_reg = command1; + tegra_qspi_writel(tqspi, QSPI_NUM_DUMMY_CYCLE(tqspi->dummy_cycles), QSPI_MISC_REG); + ret = tegra_qspi_flush_fifos(tqspi, false); if (ret < 0) return ret; @@ -974,7 +978,8 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi { struct tegra_qspi *tqspi = spi_master_get_devdata(master); struct spi_device *spi = msg->spi; - struct spi_transfer *xfer; + struct spi_transfer *xfer, *next_xfer; + bool use_hw_dummy_cycles = false; bool is_first_msg = true; int ret; @@ -984,8 +989,42 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi tqspi->rx_status = 0; list_for_each_entry(xfer, &msg->transfers, transfer_list) { + u8 dummy_cycles = 0; u32 cmd1; + /* + * Skip dummy bytes transfer if they are transferred by the hardware along + * with previous transfer. + */ + if (xfer->dummy_data && use_hw_dummy_cycles) { + msg->actual_length += xfer->len; + continue; + } + + /* + * Tegra QSPI hardware supports dummy bytes transfer after actual transfer + * bytes based on programmed dummy clock cycles in the QSPI_MISC register. + * So, check if the next transfer is dummy data transfer and program dummy + * clock cycles along with the current transfer. + */ + if (!list_is_last(&xfer->transfer_list, &msg->transfers)) { + next_xfer = list_next_entry(xfer, transfer_list); + if (next_xfer && next_xfer->dummy_data) { + dummy_cycles = next_xfer->len * 8 / next_xfer->tx_nbits; + use_hw_dummy_cycles = true; + /* + * Use software dummy bytes transfer if dummy cycles exceeds + * Tegra QSPI hardware maximum dummy cycles limit. + */ + if (dummy_cycles > QSPI_DUMMY_CYCLES_MAX) { + use_hw_dummy_cycles = false; + dummy_cycles = 0; + } + } + } + + tqspi->dummy_cycles = dummy_cycles; + reinit_completion(&tqspi->xfer_completion); cmd1 = tegra_qspi_setup_transfer_one(spi, xfer, is_first_msg);
Tegra Quad SPI controller hardware supports sending dummy bytes based on programmed dummy clock cycles after the actual transfer bytes. This patch adds this support of hardware dummy bytes transfer and skips transfer of dummy bytes from the software. For dummy cycles more than Tegra Quad SPI hardware maximum dummy cycles limit, driver transfers dummy bytes from the software. Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com> --- drivers/spi/spi-tegra210-quad.c | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-)