diff options
Diffstat (limited to 'drivers/spi/rk_spi.c')
| -rw-r--r-- | drivers/spi/rk_spi.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/drivers/spi/rk_spi.c b/drivers/spi/rk_spi.c index 0c627d9..050eacb 100644 --- a/drivers/spi/rk_spi.c +++ b/drivers/spi/rk_spi.c @@ -79,12 +79,31 @@ static void rkspi_enable_chip(struct rockchip_spi *regs, bool enable) static void rkspi_set_clk(struct rockchip_spi_priv *priv, uint speed) { - uint clk_div; + /* + * We should try not to exceed the speed requested by the caller: + * when selecting a divider, we need to make sure we round up. + */ + uint clk_div = DIV_ROUND_UP(priv->input_rate, speed); + + /* The baudrate register (BAUDR) is defined as a 32bit register where + * the upper 16bit are reserved and having 'Fsclk_out' in the lower + * 16bits with 'Fsclk_out' defined as follows: + * + * Fsclk_out = Fspi_clk/ SCKDV + * Where SCKDV is any even value between 2 and 65534. + */ + if (clk_div > 0xfffe) { + clk_div = 0xfffe; + debug("%s: can't divide down to %d hz (actual will be %d hz)\n", + __func__, speed, priv->input_rate / clk_div); + } + + /* Round up to the next even 16bit number */ + clk_div = (clk_div + 1) & 0xfffe; - clk_div = clk_get_divisor(priv->input_rate, speed); debug("spi speed %u, div %u\n", speed, clk_div); - writel(clk_div, &priv->regs->baudr); + clrsetbits_le32(&priv->regs->baudr, 0xffff, clk_div); priv->last_speed_hz = speed; } |