diff options
Diffstat (limited to 'src/cpu/samsung')
| -rw-r--r-- | src/cpu/samsung/exynos5420/spi.c | 76 |
1 files changed, 39 insertions, 37 deletions
diff --git a/src/cpu/samsung/exynos5420/spi.c b/src/cpu/samsung/exynos5420/spi.c index 82c37650da..6637aad9e8 100644 --- a/src/cpu/samsung/exynos5420/spi.c +++ b/src/cpu/samsung/exynos5420/spi.c @@ -102,6 +102,26 @@ void spi_cs_deactivate(struct spi_slave *slave) setbits_le32(®s->cs_reg, SPI_SLAVE_SIG_INACT); } +static inline void exynos_spi_soft_reset(struct exynos_spi *regs) +{ + /* The soft reset clears only FIFO and status register. + * All special function registers are not changed. */ + setbits_le32(®s->ch_cfg, SPI_CH_RST); + clrbits_le32(®s->ch_cfg, SPI_CH_RST); +} + +static inline void exynos_spi_flush_fifo(struct exynos_spi *regs) +{ + /* + * Flush spi tx, rx fifos and reset the SPI controller + * and clear rx/tx channel + */ + clrbits_le32(®s->ch_cfg, SPI_RX_CH_ON | SPI_TX_CH_ON); + clrbits_le32(®s->ch_cfg, SPI_CH_HS_EN); + exynos_spi_soft_reset(regs); + setbits_le32(®s->ch_cfg, SPI_RX_CH_ON | SPI_TX_CH_ON); +} + static void exynos_spi_rx_tx(struct exynos_spi *regs, int todo, void *dinp, void const *doutp, int i) { @@ -114,8 +134,7 @@ static void exynos_spi_rx_tx(struct exynos_spi *regs, int todo, ASSERT(todo % 4 == 0); out_bytes = in_bytes = todo; - setbits_le32(®s->ch_cfg, SPI_CH_RST); - clrbits_le32(®s->ch_cfg, SPI_CH_RST); + exynos_spi_soft_reset(regs); writel(((todo * 8) / 32) | SPI_PACKET_CNT_EN, ®s->pkt_cnt); while (in_bytes) { @@ -143,35 +162,27 @@ static void exynos_spi_rx_tx(struct exynos_spi *regs, int todo, } } -/* set up SPI channel */ int spi_claim_bus(struct spi_slave *slave) { struct exynos_spi_slave *espi = to_exynos_spi(slave); struct exynos_spi *regs = espi->regs; - /* set the spi1 GPIO */ + exynos_spi_flush_fifo(regs); - /* set pktcnt and enable it */ - writel(4 | SPI_PACKET_CNT_EN, ®s->pkt_cnt); - /* set FB_CLK_SEL */ - writel(SPI_FB_DELAY_180, ®s->fb_clk); - /* set CH_WIDTH and BUS_WIDTH as word */ - setbits_le32(®s->mode_cfg, - SPI_MODE_CH_WIDTH_WORD | SPI_MODE_BUS_WIDTH_WORD); - clrbits_le32(®s->ch_cfg, SPI_CH_CPOL_L); /* CPOL: active high */ + // Select Active High Clock, Format A (SCP 30.2.1.8). + clrbits_le32(®s->ch_cfg, SPI_CH_CPOL_L | SPI_CH_CPHA_B); - /* clear rx and tx channel if set priveously */ - clrbits_le32(®s->ch_cfg, SPI_RX_CH_ON | SPI_TX_CH_ON); - - setbits_le32(®s->swap_cfg, - SPI_RX_SWAP_EN | SPI_RX_BYTE_SWAP | SPI_RX_HWORD_SWAP); - - /* do a soft reset */ - setbits_le32(®s->ch_cfg, SPI_CH_RST); - clrbits_le32(®s->ch_cfg, SPI_CH_RST); + // Set FeedBack Clock Selection. + writel(SPI_FB_DELAY_180, ®s->fb_clk); - /* now set rx and tx channel ON */ - setbits_le32(®s->ch_cfg, SPI_RX_CH_ON | SPI_TX_CH_ON | SPI_CH_HS_EN); + // HIGH speed is required for Tx/Rx to work in 50MHz (SCP 30.2.1.6). + if (espi->half_duplex) { + clrbits_le32(®s->ch_cfg, SPI_CH_HS_EN); + printk(BIOS_DEBUG, "%s: LOW speed.\n", __func__); + } else { + setbits_le32(®s->ch_cfg, SPI_CH_HS_EN); + printk(BIOS_DEBUG, "%s: HIGH speed.\n", __func__); + } return 0; } @@ -209,21 +220,12 @@ static int exynos_spi_read(struct spi_slave *slave, void *dest, uint32_t len, void spi_release_bus(struct spi_slave *slave) { struct exynos_spi *regs = to_exynos_spi(slave)->regs; - /* - * Let put controller mode to BYTE as - * SPI driver does not support WORD mode yet - */ - clrbits_le32(®s->mode_cfg, - SPI_MODE_CH_WIDTH_WORD | SPI_MODE_BUS_WIDTH_WORD); + /* Reset swap mode to make sure no one relying on default values (Ex, + * payload or kernel) will go wrong. */ + clrbits_le32(®s->mode_cfg, (SPI_MODE_CH_WIDTH_WORD | + SPI_MODE_BUS_WIDTH_WORD)); writel(0, ®s->swap_cfg); - - /* - * Flush spi tx, rx fifos and reset the SPI controller - * and clear rx/tx channel - */ - clrsetbits_le32(®s->ch_cfg, SPI_CH_HS_EN, SPI_CH_RST); - clrbits_le32(®s->ch_cfg, SPI_CH_RST); - clrbits_le32(®s->ch_cfg, SPI_TX_CH_ON | SPI_RX_CH_ON); + exynos_spi_flush_fifo(regs); } // SPI as CBFS media. |