Extend the SPI bus API a bit. The config structure gets an sc_cs_delay

member to allow us to specify a delay between assert the CS# signal and
starting the clock.  And the transfer function gains a flags argument,
which can be used to specify a new SPI_KEEP_CS flag to keep CS# asserted
after the transfer.  This allows us to do another transfer immediately
afterwards without de-asserting CS# which is necessary for sending
commands to the upcoming Apple M1 keyboard/touchpad driver.

ok patrick@

3 files changed, 33 insertions, 21 deletions

diff --git a/sys/dev/fdt/imxspi.c b/sys/dev/fdt/imxspi.c
index 425c3cba968..3c07fe68b17 100644
--- a/sys/dev/fdt/imxspi.c
+++ b/sys/dev/fdt/imxspi.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: imxspi.c,v 1.2 2021/10/24 17:52:26 mpi Exp $ */
+/* $OpenBSD: imxspi.c,v 1.3 2021/10/31 15:12:00 kettenis Exp $ */
 /*
  * Copyright (c) 2018 Patrick Wildt <patrick@blueri.se>
  *
@@ -99,6 +99,7 @@ struct imxspi_softc {
 	int			 sc_ridx;
 	int			 sc_widx;
 	int			 sc_cs;
+	u_int			 sc_cs_delay;
 };
 
 int	 imxspi_match(struct device *, void *, void *);
@@ -109,7 +110,7 @@ int	 imxspi_intr(void *);
 
 void	 imxspi_config(void *, struct spi_config *);
 uint32_t imxspi_clkdiv(struct imxspi_softc *, uint32_t);
-int	 imxspi_transfer(void *, char *, char *, int);
+int	 imxspi_transfer(void *, char *, char *, int, int);
 int	 imxspi_acquire_bus(void *, int);
 void	 imxspi_release_bus(void *, int);
 
@@ -235,6 +236,7 @@ imxspi_config(void *cookie, struct spi_config *conf)
 		return;
 	}
 	sc->sc_cs = cs;
+	sc->sc_cs_delay = conf->sc_cs_delay;
 
 	conreg = SPI_CONREG_EN;
 	conreg |= SPI_CONREG_CHANNEL_MASTER;
@@ -322,7 +324,7 @@ imxspi_find_cs_gpio(struct imxspi_softc *sc, int cs)
 }
 
 int
-imxspi_transfer(void *cookie, char *out, char *in, int len)
+imxspi_transfer(void *cookie, char *out, char *in, int len, int flags)
 {
 	struct imxspi_softc *sc = cookie;
 	uint32_t *gpio;
@@ -335,6 +337,7 @@ imxspi_transfer(void *cookie, char *out, char *in, int len)
 		gpio_controller_set_pin(gpio, 0);
 		delay(1);
 	}
+	delay(sc->sc_cs_delay);
 
 	/* drain input buffer */
 	while (HREAD4(sc, SPI_STATREG) & SPI_STATREG_RR)
@@ -370,10 +373,12 @@ imxspi_transfer(void *cookie, char *out, char *in, int len)
 		HWRITE4(sc, SPI_STATREG, SPI_STATREG_TC);
 	}
 
-	gpio = imxspi_find_cs_gpio(sc, sc->sc_cs);
-	if (gpio) {
-		gpio_controller_set_pin(gpio, 1);
-		delay(1);
+	if (!ISSET(flags, SPI_KEEP_CS)) {
+		gpio = imxspi_find_cs_gpio(sc, sc->sc_cs);
+		if (gpio) {
+			gpio_controller_set_pin(gpio, 1);
+			delay(1);
+		}
 	}
 
 	return 0;
diff --git a/sys/dev/fdt/mvspi.c b/sys/dev/fdt/mvspi.c
index 4731e349f3e..30b8831dbb5 100644
--- a/sys/dev/fdt/mvspi.c
+++ b/sys/dev/fdt/mvspi.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mvspi.c,v 1.2 2021/10/24 17:52:26 mpi Exp $ */
+/* $OpenBSD: mvspi.c,v 1.3 2021/10/31 15:12:00 kettenis Exp $ */
 /*
  * Copyright (c) 2019 Patrick Wildt <patrick@blueri.se>
  *
@@ -60,6 +60,7 @@ struct mvspi_softc {
 	struct spi_controller	 sc_tag;
 
 	int			 sc_cs;
+	u_int			 sc_cs_delay;
 };
 
 int	 mvspi_match(struct device *, void *, void *);
@@ -68,7 +69,7 @@ int	 mvspi_detach(struct device *, int);
 
 void	 mvspi_config(void *, struct spi_config *);
 uint32_t mvspi_clkdiv(struct mvspi_softc *, uint32_t);
-int	 mvspi_transfer(void *, char *, char *, int);
+int	 mvspi_transfer(void *, char *, char *, int, int);
 int	 mvspi_acquire_bus(void *, int);
 void	 mvspi_release_bus(void *, int);
 
@@ -177,6 +178,7 @@ mvspi_config(void *cookie, struct spi_config *conf)
 		return;
 	}
 	sc->sc_cs = cs;
+	sc->sc_cs_delay = conf->sc_cs_delay;
 
 	HCLR4(sc, SPI_CFG, SPI_CFG_PRESCALE_MASK);
 	HSET4(sc, SPI_CFG, mvspi_clkdiv(sc, conf->sc_freq));
@@ -229,12 +231,13 @@ mvspi_set_cs(struct mvspi_softc *sc, int cs, int on)
 }
 
 int
-mvspi_transfer(void *cookie, char *out, char *in, int len)
+mvspi_transfer(void *cookie, char *out, char *in, int len, int flags)
 {
 	struct mvspi_softc *sc = cookie;
 	int i = 0;
 
 	mvspi_set_cs(sc, sc->sc_cs, 1);
+	delay(sc->sc_cs_delay);
 
 	while (i < len) {
 		if (mvspi_wait_state(sc, SPI_CTRL_XFER_READY,
@@ -255,7 +258,8 @@ mvspi_transfer(void *cookie, char *out, char *in, int len)
 		i++;
 	}
 
-	mvspi_set_cs(sc, sc->sc_cs, 0);
+	if (!ISSET(flags, SPI_KEEP_CS))
+		mvspi_set_cs(sc, sc->sc_cs, 0);
 	return 0;
 
 err:
diff --git a/sys/dev/spi/spivar.h b/sys/dev/spi/spivar.h
index 986bc7f602d..c56b840a3b6 100644
--- a/sys/dev/spi/spivar.h
+++ b/sys/dev/spi/spivar.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: spivar.h,v 1.1 2018/07/26 10:59:07 patrick Exp $ */
+/* $OpenBSD: spivar.h,v 1.2 2021/10/31 15:12:00 kettenis Exp $ */
 /*
  * Copyright (c) 2018 Patrick Wildt <patrick@blueri.se>
  *
@@ -23,14 +23,17 @@ struct spi_config {
 #define SPI_CONFIG_CS_HIGH	(1 << 2)
 	int		 sc_bpw;
 	uint32_t	 sc_freq;
+	u_int		 sc_cs_delay;
 };
 
+#define SPI_KEEP_CS		(1 << 0)
+
 typedef struct spi_controller {
-	void			*sc_cookie;
-	void			(*sc_config)(void *, struct spi_config *);
-	int			(*sc_transfer)(void *, char *, char *, int);
-	int			(*sc_acquire_bus)(void *, int);
-	void			(*sc_release_bus)(void *, int);
+	void		*sc_cookie;
+	void		(*sc_config)(void *, struct spi_config *);
+	int		(*sc_transfer)(void *, char *, char *, int, int);
+	int		(*sc_acquire_bus)(void *, int);
+	void		(*sc_release_bus)(void *, int);
 } *spi_tag_t;
 
 struct spi_attach_args {
@@ -42,11 +45,11 @@ struct spi_attach_args {
 #define	spi_config(sc, config)						\
 	(*(sc)->sc_config)((sc)->sc_cookie, (config))
 #define	spi_read(sc, data, len)						\
-	(*(sc)->sc_transfer)((sc)->sc_cookie, NULL, (data), (len))
+	(*(sc)->sc_transfer)((sc)->sc_cookie, NULL, (data), (len), 0)
 #define	spi_write(sc, data, len)					\
-	(*(sc)->sc_transfer)((sc)->sc_cookie, (data), NULL, (len))
-#define	spi_transfer(sc, out, in, len)					\
-	(*(sc)->sc_transfer)((sc)->sc_cookie, (out), (in), (len))
+	(*(sc)->sc_transfer)((sc)->sc_cookie, (data), NULL, (len), 0)
+#define	spi_transfer(sc, out, in, len, flags)				\
+	(*(sc)->sc_transfer)((sc)->sc_cookie, (out), (in), (len), (flags))
 #define	spi_acquire_bus(sc, flags)					\
 	(*(sc)->sc_acquire_bus)((sc)->sc_cookie, (flags))
 #define	spi_release_bus(sc, flags)					\