[PATCH 6.1 058/185] serial: sc16is7xx: improve regmap debugfs by using one regmap per port

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

commit 3837a0379533aabb9e4483677077479f7c6aa910 upstream.

With this current driver regmap implementation, it is hard to make sense
of the register addresses displayed using the regmap debugfs interface,
because they do not correspond to the actual register addresses documented
in the datasheet. For example, register 1 is displayed as registers 04 thru
07:

$ cat /sys/kernel/debug/regmap/spi0.0/registers
  04: 10 -> Port 0, register offset 1
  05: 10 -> Port 1, register offset 1
  06: 00 -> Port 2, register offset 1 -> invalid
  07: 00 -> port 3, register offset 1 -> invalid
  ...

The reason is that bits 0 and 1 of the register address correspond to the
channel (port) bits, so the register address itself starts at bit 2, and we
must 'mentally' shift each register address by 2 bits to get its real
address/offset.

Also, only channels 0 and 1 are supported by the chip, so channel mask
combinations of 10b and 11b are invalid, and the display of these
registers is useless.

This patch adds a separate regmap configuration for each port, similar to
what is done in the max310x driver, so that register addresses displayed
match the register addresses in the chip datasheet. Also, each port now has
its own debugfs entry.

Example with new regmap implementation:

$ cat /sys/kernel/debug/regmap/spi0.0-port0/registers
1: 10
2: 01
3: 00
...

$ cat /sys/kernel/debug/regmap/spi0.0-port1/registers
1: 10
2: 01
3: 00

As an added bonus, this also simplifies some operations (read/write/modify)
because it is no longer necessary to manually shift register addresses.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231030211447.974779-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/sc16is7xx.c |  143 +++++++++++++++++++++++------------------
 1 file changed, 81 insertions(+), 62 deletions(-)

--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -301,8 +301,8 @@
 
 
 /* Misc definitions */
+#define SC16IS7XX_SPI_READ_BIT		BIT(7)
 #define SC16IS7XX_FIFO_SIZE		(64)
-#define SC16IS7XX_REG_SHIFT		2
 #define SC16IS7XX_GPIOS_PER_BANK	4
 
 struct sc16is7xx_devtype {
@@ -324,6 +324,7 @@ struct sc16is7xx_one_config {
 struct sc16is7xx_one {
 	struct uart_port		port;
 	u8				line;
+	struct regmap			*regmap;
 	struct kthread_work		tx_work;
 	struct kthread_work		reg_work;
 	struct kthread_delayed_work	ms_work;
@@ -362,48 +363,37 @@ static void sc16is7xx_stop_tx(struct uar
 #define to_sc16is7xx_port(p,e)	((container_of((p), struct sc16is7xx_port, e)))
 #define to_sc16is7xx_one(p,e)	((container_of((p), struct sc16is7xx_one, e)))
 
-static int sc16is7xx_line(struct uart_port *port)
-{
-	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
-
-	return one->line;
-}
-
 static u8 sc16is7xx_port_read(struct uart_port *port, u8 reg)
 {
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 	unsigned int val = 0;
-	const u8 line = sc16is7xx_line(port);
 
-	regmap_read(s->regmap, (reg << SC16IS7XX_REG_SHIFT) | line, &val);
+	regmap_read(one->regmap, reg, &val);
 
 	return val;
 }
 
 static void sc16is7xx_port_write(struct uart_port *port, u8 reg, u8 val)
 {
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
-	const u8 line = sc16is7xx_line(port);
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 
-	regmap_write(s->regmap, (reg << SC16IS7XX_REG_SHIFT) | line, val);
+	regmap_write(one->regmap, reg, val);
 }
 
 static void sc16is7xx_fifo_read(struct uart_port *port, unsigned int rxlen)
 {
 	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
-	const u8 line = sc16is7xx_line(port);
-	u8 addr = (SC16IS7XX_RHR_REG << SC16IS7XX_REG_SHIFT) | line;
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 
-	regcache_cache_bypass(s->regmap, true);
-	regmap_raw_read(s->regmap, addr, s->buf, rxlen);
-	regcache_cache_bypass(s->regmap, false);
+	regcache_cache_bypass(one->regmap, true);
+	regmap_raw_read(one->regmap, SC16IS7XX_RHR_REG, s->buf, rxlen);
+	regcache_cache_bypass(one->regmap, false);
 }
 
 static void sc16is7xx_fifo_write(struct uart_port *port, u8 to_send)
 {
 	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
-	const u8 line = sc16is7xx_line(port);
-	u8 addr = (SC16IS7XX_THR_REG << SC16IS7XX_REG_SHIFT) | line;
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 
 	/*
 	 * Don't send zero-length data, at least on SPI it confuses the chip
@@ -412,19 +402,17 @@ static void sc16is7xx_fifo_write(struct
 	if (unlikely(!to_send))
 		return;
 
-	regcache_cache_bypass(s->regmap, true);
-	regmap_raw_write(s->regmap, addr, s->buf, to_send);
-	regcache_cache_bypass(s->regmap, false);
+	regcache_cache_bypass(one->regmap, true);
+	regmap_raw_write(one->regmap, SC16IS7XX_THR_REG, s->buf, to_send);
+	regcache_cache_bypass(one->regmap, false);
 }
 
 static void sc16is7xx_port_update(struct uart_port *port, u8 reg,
 				  u8 mask, u8 val)
 {
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
-	const u8 line = sc16is7xx_line(port);
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 
-	regmap_update_bits(s->regmap, (reg << SC16IS7XX_REG_SHIFT) | line,
-			   mask, val);
+	regmap_update_bits(one->regmap, reg, mask, val);
 }
 
 static int sc16is7xx_alloc_line(void)
@@ -479,7 +467,7 @@ static const struct sc16is7xx_devtype sc
 
 static bool sc16is7xx_regmap_volatile(struct device *dev, unsigned int reg)
 {
-	switch (reg >> SC16IS7XX_REG_SHIFT) {
+	switch (reg) {
 	case SC16IS7XX_RHR_REG:
 	case SC16IS7XX_IIR_REG:
 	case SC16IS7XX_LSR_REG:
@@ -498,7 +486,7 @@ static bool sc16is7xx_regmap_volatile(st
 
 static bool sc16is7xx_regmap_precious(struct device *dev, unsigned int reg)
 {
-	switch (reg >> SC16IS7XX_REG_SHIFT) {
+	switch (reg) {
 	case SC16IS7XX_RHR_REG:
 		return true;
 	default:
@@ -511,6 +499,7 @@ static bool sc16is7xx_regmap_precious(st
 static int sc16is7xx_set_baud(struct uart_port *port, int baud)
 {
 	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 	u8 lcr;
 	u8 prescaler = 0;
 	unsigned long clk = port->uartclk, div = clk / 16 / baud;
@@ -542,12 +531,12 @@ static int sc16is7xx_set_baud(struct uar
 			     SC16IS7XX_LCR_CONF_MODE_B);
 
 	/* Enable enhanced features */
-	regcache_cache_bypass(s->regmap, true);
+	regcache_cache_bypass(one->regmap, true);
 	sc16is7xx_port_update(port, SC16IS7XX_EFR_REG,
 			      SC16IS7XX_EFR_ENABLE_BIT,
 			      SC16IS7XX_EFR_ENABLE_BIT);
 
-	regcache_cache_bypass(s->regmap, false);
+	regcache_cache_bypass(one->regmap, false);
 
 	/* Put LCR back to the normal mode */
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
@@ -563,10 +552,10 @@ static int sc16is7xx_set_baud(struct uar
 			     SC16IS7XX_LCR_CONF_MODE_A);
 
 	/* Write the new divisor */
-	regcache_cache_bypass(s->regmap, true);
+	regcache_cache_bypass(one->regmap, true);
 	sc16is7xx_port_write(port, SC16IS7XX_DLH_REG, div / 256);
 	sc16is7xx_port_write(port, SC16IS7XX_DLL_REG, div % 256);
-	regcache_cache_bypass(s->regmap, false);
+	regcache_cache_bypass(one->regmap, false);
 
 	/* Put LCR back to the normal mode */
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
@@ -1094,7 +1083,7 @@ static void sc16is7xx_set_termios(struct
 			     SC16IS7XX_LCR_CONF_MODE_B);
 
 	/* Configure flow control */
-	regcache_cache_bypass(s->regmap, true);
+	regcache_cache_bypass(one->regmap, true);
 	sc16is7xx_port_write(port, SC16IS7XX_XON1_REG, termios->c_cc[VSTART]);
 	sc16is7xx_port_write(port, SC16IS7XX_XOFF1_REG, termios->c_cc[VSTOP]);
 
@@ -1113,7 +1102,7 @@ static void sc16is7xx_set_termios(struct
 			      SC16IS7XX_EFR_REG,
 			      SC16IS7XX_EFR_FLOWCTRL_BITS,
 			      flow);
-	regcache_cache_bypass(s->regmap, false);
+	regcache_cache_bypass(one->regmap, false);
 
 	/* Update LCR register */
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
@@ -1164,7 +1153,6 @@ static int sc16is7xx_config_rs485(struct
 static int sc16is7xx_startup(struct uart_port *port)
 {
 	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
 	unsigned int val;
 	unsigned long flags;
 
@@ -1181,7 +1169,7 @@ static int sc16is7xx_startup(struct uart
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
 			     SC16IS7XX_LCR_CONF_MODE_B);
 
-	regcache_cache_bypass(s->regmap, true);
+	regcache_cache_bypass(one->regmap, true);
 
 	/* Enable write access to enhanced features and internal clock div */
 	sc16is7xx_port_update(port, SC16IS7XX_EFR_REG,
@@ -1199,7 +1187,7 @@ static int sc16is7xx_startup(struct uart
 			     SC16IS7XX_TCR_RX_RESUME(24) |
 			     SC16IS7XX_TCR_RX_HALT(48));
 
-	regcache_cache_bypass(s->regmap, false);
+	regcache_cache_bypass(one->regmap, false);
 
 	/* Now, initialize the UART */
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, SC16IS7XX_LCR_WORD_LEN_8);
@@ -1457,7 +1445,7 @@ static int sc16is7xx_setup_mctrl_ports(s
 	if (s->mctrl_mask)
 		regmap_update_bits(
 			s->regmap,
-			SC16IS7XX_IOCONTROL_REG << SC16IS7XX_REG_SHIFT,
+			SC16IS7XX_IOCONTROL_REG,
 			SC16IS7XX_IOCONTROL_MODEM_A_BIT |
 			SC16IS7XX_IOCONTROL_MODEM_B_BIT, s->mctrl_mask);
 
@@ -1472,7 +1460,7 @@ static const struct serial_rs485 sc16is7
 
 static int sc16is7xx_probe(struct device *dev,
 			   const struct sc16is7xx_devtype *devtype,
-			   struct regmap *regmap, int irq)
+			   struct regmap *regmaps[], int irq)
 {
 	unsigned long freq = 0, *pfreq = dev_get_platdata(dev);
 	unsigned int val;
@@ -1480,16 +1468,16 @@ static int sc16is7xx_probe(struct device
 	int i, ret;
 	struct sc16is7xx_port *s;
 
-	if (IS_ERR(regmap))
-		return PTR_ERR(regmap);
+	for (i = 0; i < devtype->nr_uart; i++)
+		if (IS_ERR(regmaps[i]))
+			return PTR_ERR(regmaps[i]);
 
 	/*
 	 * This device does not have an identification register that would
 	 * tell us if we are really connected to the correct device.
 	 * The best we can do is to check if communication is at all possible.
 	 */
-	ret = regmap_read(regmap,
-			  SC16IS7XX_LSR_REG << SC16IS7XX_REG_SHIFT, &val);
+	ret = regmap_read(regmaps[0], SC16IS7XX_LSR_REG, &val);
 	if (ret < 0)
 		return -EPROBE_DEFER;
 
@@ -1523,7 +1511,7 @@ static int sc16is7xx_probe(struct device
 			return -EINVAL;
 	}
 
-	s->regmap = regmap;
+	s->regmap = regmaps[0];
 	s->devtype = devtype;
 	dev_set_drvdata(dev, s);
 	mutex_init(&s->efr_lock);
@@ -1538,8 +1526,8 @@ static int sc16is7xx_probe(struct device
 	sched_set_fifo(s->kworker_task);
 
 	/* reset device, purging any pending irq / data */
-	regmap_write(s->regmap, SC16IS7XX_IOCONTROL_REG << SC16IS7XX_REG_SHIFT,
-			SC16IS7XX_IOCONTROL_SRESET_BIT);
+	regmap_write(s->regmap, SC16IS7XX_IOCONTROL_REG,
+		     SC16IS7XX_IOCONTROL_SRESET_BIT);
 
 	for (i = 0; i < devtype->nr_uart; ++i) {
 		s->p[i].line		= i;
@@ -1563,6 +1551,7 @@ static int sc16is7xx_probe(struct device
 		s->p[i].port.ops	= &sc16is7xx_ops;
 		s->p[i].old_mctrl	= 0;
 		s->p[i].port.line	= sc16is7xx_alloc_line();
+		s->p[i].regmap		= regmaps[i];
 
 		if (s->p[i].port.line >= SC16IS7XX_MAX_DEVS) {
 			ret = -ENOMEM;
@@ -1591,13 +1580,13 @@ static int sc16is7xx_probe(struct device
 		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_LCR_REG,
 				     SC16IS7XX_LCR_CONF_MODE_B);
 
-		regcache_cache_bypass(s->regmap, true);
+		regcache_cache_bypass(regmaps[i], true);
 
 		/* Enable write access to enhanced features */
 		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_EFR_REG,
 				     SC16IS7XX_EFR_ENABLE_BIT);
 
-		regcache_cache_bypass(s->regmap, false);
+		regcache_cache_bypass(regmaps[i], false);
 
 		/* Restore access to general registers */
 		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_LCR_REG, 0x00);
@@ -1700,19 +1689,36 @@ static const struct of_device_id __maybe
 MODULE_DEVICE_TABLE(of, sc16is7xx_dt_ids);
 
 static struct regmap_config regcfg = {
-	.reg_bits = 7,
-	.pad_bits = 1,
+	.reg_bits = 5,
+	.pad_bits = 3,
 	.val_bits = 8,
 	.cache_type = REGCACHE_RBTREE,
 	.volatile_reg = sc16is7xx_regmap_volatile,
 	.precious_reg = sc16is7xx_regmap_precious,
+	.max_register = SC16IS7XX_EFCR_REG,
 };
 
+static const char *sc16is7xx_regmap_name(unsigned int port_id)
+{
+	static char buf[6];
+
+	snprintf(buf, sizeof(buf), "port%d", port_id);
+
+	return buf;
+}
+
+static unsigned int sc16is7xx_regmap_port_mask(unsigned int port_id)
+{
+	/* CH1,CH0 are at bits 2:1. */
+	return port_id << 1;
+}
+
 #ifdef CONFIG_SERIAL_SC16IS7XX_SPI
 static int sc16is7xx_spi_probe(struct spi_device *spi)
 {
 	const struct sc16is7xx_devtype *devtype;
-	struct regmap *regmap;
+	struct regmap *regmaps[2];
+	unsigned int i;
 	int ret;
 
 	/* Setup SPI bus */
@@ -1737,11 +1743,20 @@ static int sc16is7xx_spi_probe(struct sp
 		devtype = (struct sc16is7xx_devtype *)id_entry->driver_data;
 	}
 
-	regcfg.max_register = (0xf << SC16IS7XX_REG_SHIFT) |
-			      (devtype->nr_uart - 1);
-	regmap = devm_regmap_init_spi(spi, &regcfg);
+	for (i = 0; i < devtype->nr_uart; i++) {
+		regcfg.name = sc16is7xx_regmap_name(i);
+		/*
+		 * If read_flag_mask is 0, the regmap code sets it to a default
+		 * of 0x80. Since we specify our own mask, we must add the READ
+		 * bit ourselves:
+		 */
+		regcfg.read_flag_mask = sc16is7xx_regmap_port_mask(i) |
+			SC16IS7XX_SPI_READ_BIT;
+		regcfg.write_flag_mask = sc16is7xx_regmap_port_mask(i);
+		regmaps[i] = devm_regmap_init_spi(spi, &regcfg);
+	}
 
-	return sc16is7xx_probe(&spi->dev, devtype, regmap, spi->irq);
+	return sc16is7xx_probe(&spi->dev, devtype, regmaps, spi->irq);
 }
 
 static void sc16is7xx_spi_remove(struct spi_device *spi)
@@ -1780,7 +1795,8 @@ static int sc16is7xx_i2c_probe(struct i2
 			       const struct i2c_device_id *id)
 {
 	const struct sc16is7xx_devtype *devtype;
-	struct regmap *regmap;
+	struct regmap *regmaps[2];
+	unsigned int i;
 
 	if (i2c->dev.of_node) {
 		devtype = device_get_match_data(&i2c->dev);
@@ -1790,11 +1806,14 @@ static int sc16is7xx_i2c_probe(struct i2
 		devtype = (struct sc16is7xx_devtype *)id->driver_data;
 	}
 
-	regcfg.max_register = (0xf << SC16IS7XX_REG_SHIFT) |
-			      (devtype->nr_uart - 1);
-	regmap = devm_regmap_init_i2c(i2c, &regcfg);
+	for (i = 0; i < devtype->nr_uart; i++) {
+		regcfg.name = sc16is7xx_regmap_name(i);
+		regcfg.read_flag_mask = sc16is7xx_regmap_port_mask(i);
+		regcfg.write_flag_mask = sc16is7xx_regmap_port_mask(i);
+		regmaps[i] = devm_regmap_init_i2c(i2c, &regcfg);
+	}
 
-	return sc16is7xx_probe(&i2c->dev, devtype, regmap, i2c->irq);
+	return sc16is7xx_probe(&i2c->dev, devtype, regmaps, i2c->irq);
 }
 
 static void sc16is7xx_i2c_remove(struct i2c_client *client)