[PATCH 9/9] misc: add FPC202 dual port controller driver

Romain Gantois
2024-11-08T15:37:18Z

The TI FPC202 dual port controller serves as a low- speed signal aggregator
for common port types such as SFP, QSFP, Mini-SAS HD, and others.

It aggregates GPIO and I2C signals across two downstream ports, acting as
both a GPIO controller and an I2C address translator for up to two logical
devices per port.

Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>
---
MAINTAINERS | 7 +
drivers/misc/Kconfig | 11 ++
drivers/misc/Makefile | 1 +
drivers/misc/ti_fpc202.c | 421 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 440 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index c27f3190737f8b85779bde5489639c8b899f4fd8..4e686d6652f0395f4f2baf1e598aa6023a255a25 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -23223,6 +23223,13 @@ F: drivers/misc/tifm*
F: drivers/mmc/host/tifm_sd.c
F: include/linux/tifm.h

+TI FPC202 DUAL PORT CONTROLLER
+M: Romain Gantois <romain.gantois@bootlin.com>
+L: linux-kernel@vger.kernel.org
+S: Maintained
+F: Documentation/devicetree/bindings/misc/ti,fpc202.yaml
+F: drivers/misc/ti_fpc202.c
+
TI FPD-LINK DRIVERS
M: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
L: linux-media@vger.kernel.org
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 3fe7e2a9bd294da562cf553d958772dcb49bbc89..2549989422c5b1a67a886290efcd692c0835c7e1 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -114,6 +114,17 @@ config RPMB

If unsure, select N.

+config TI_FPC202
+ tristate "TI FPC202 Dual Port Controller"
+ select GPIOLIB
+ depends on I2C_ATR
+ help
+ If you say yes here you get support for the Texas Instruments FPC202
+ Dual Port Controller.
+
+ This driver can also be built as a module. If so, the module will be
+ called fpc202.
+
config TIFM_CORE
tristate "TI Flash Media interface support"
depends on PCI
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index a9f94525e1819d5d7eed4937ce1d50b2875ee71b..d0b7a1b96619b3125d1455d40268040e0764b341 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_ATMEL_SSC) += atmel-ssc.o
obj-$(CONFIG_DUMMY_IRQ) += dummy-irq.o
obj-$(CONFIG_ICS932S401) += ics932s401.o
obj-$(CONFIG_LKDTM) += lkdtm/
+obj-$(CONFIG_TI_FPC202) += ti_fpc202.o
obj-$(CONFIG_TIFM_CORE) += tifm_core.o
obj-$(CONFIG_TIFM_7XX1) += tifm_7xx1.o
obj-$(CONFIG_PHANTOM) += phantom.o
diff --git a/drivers/misc/ti_fpc202.c b/drivers/misc/ti_fpc202.c
new file mode 100644
index 0000000000000000000000000000000000000000..c2a720e10fa1391da43f469efb5f7ccd49320d44
--- /dev/null
+++ b/drivers/misc/ti_fpc202.c
@@ -0,0 +1,421 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ti_fpc202.c - FPC202 Dual Port Controller driver
+ *
+ * Copyright (C) 2024 Bootlin
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/i2c-atr.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/module.h>
+
+#define FPC202_ALIASES_PER_PORT 2
+
+/*
+ * GPIO: port mapping
+ *
+ * 0: P0_S0_IN_A
+ * 1: P0_S1_IN_A
+ * 2: P1_S0_IN_A
+ * 3: P1_S1_IN_A
+ * 4: P0_S0_IN_B
+ * ...
+ * 8: P0_S0_IN_C
+ * ...
+ * 12: P0_S0_OUT_A
+ * ...
+ * 16: P0_S0_OUT_B
+ * ...
+ * 19: P1_S1_OUT_B
+ *
+ */
+
+#define FPC202_GPIO_COUNT 20
+#define FPC202_GPIO_P0_S0_IN_B 4
+#define FPC202_GPIO_P0_S0_OUT_A 12
+
+#define FPC202_REG_IN_A_INT 0x6
+#define FPC202_REG_IN_C_IN_B 0x7
+#define FPC202_REG_OUT_A_OUT_B 0x8
+
+#define FPC202_REG_OUT_A_OUT_B_VAL 0xa
+
+#define FPC202_REG_MOD_DEV(port, dev) (0xb4 + ((port) * 4) + (dev))
+#define FPC202_REG_AUX_DEV(port, dev) (0xb6 + ((port) * 4) + (dev))
+
+/*
+ * The FPC202 doesn't support turning off address translation on a single port.
+ * So just set an invalid I2C address as the translation target when no client
+ * address is attached.
+ */
+#define FPC202_REG_DEV_INVALID 0
+
+/* Even aliases are assigned to device 0 and odd aliases to device 1 */
+#define fpc202_dev_num_from_alias(alias) ((alias) % 2)
+
+struct fpc202_priv {
+ struct i2c_client *client;
+ struct i2c_atr *atr;
+ struct gpio_desc *en_gpio;
+ struct gpio_chip gpio;
+
+ /* Lock REG_MOD/AUX_DEV and addr_caches during attach/detach */
+ struct mutex reg_dev_lock;
+
+ /* Cached device addresses for both ports and their devices */
+ u8 addr_caches[2][2];
+};
+
+static void fpc202_fill_alias_table(struct i2c_client *client, u16 *aliases, int port_id)
+{
+ u16 first_alias;
+ int i;
+
+ /*
+ * There is a predefined list of aliases for each FPC202 I2C
+ * self-address. This allows daisy-chained FPC202 units to
+ * automatically take on different sets of aliases.
+ * Each port of an FPC202 unit is assigned two aliases from this list.
+ */
+ first_alias = 0x10 + 4 * port_id + 8 * ((u16)client->addr - 2);
+
+ for (i = 0; i < FPC202_ALIASES_PER_PORT; i++)
+ aliases[i] = first_alias + i;
+}
+
+static int fpc202_gpio_get_dir(int offset)
+{
+ return offset < FPC202_GPIO_P0_S0_OUT_A ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT;
+}
+
+static int fpc202_read(struct fpc202_priv *priv, u8 reg)
+{
+ int val;
+
+ val = i2c_smbus_read_byte_data(priv->client, reg);
+ return val;
+}
+
+static int fpc202_write(struct fpc202_priv *priv, u8 reg, u8 value)
+{
+ return i2c_smbus_write_byte_data(priv->client, reg, value);
+}
+
+static void fpc202_set_enable(struct fpc202_priv *priv, int enable)
+{
+ if (!priv->en_gpio)
+ return;
+
+ gpiod_set_value(priv->en_gpio, enable);
+}
+
+static void fpc202_gpio_set(struct gpio_chip *chip, unsigned int offset,
+ int value)
+{
+ struct fpc202_priv *priv = gpiochip_get_data(chip);
+ int ret;
+ u8 val;
+
+ if (fpc202_gpio_get_dir(offset) == GPIO_LINE_DIRECTION_IN)
+ return;
+
+ ret = fpc202_read(priv, FPC202_REG_OUT_A_OUT_B_VAL);
+ if (ret < 0) {
+ dev_err(&priv->client->dev, "Failed to set GPIO %d value! err %d\n", offset, ret);
+ return;
+ }
+
+ val = (u8)ret;
+
+ if (value)
+ val |= BIT(offset - FPC202_GPIO_P0_S0_OUT_A);
+ else
+ val &= ~BIT(offset - FPC202_GPIO_P0_S0_OUT_A);
+
+ fpc202_write(priv, FPC202_REG_OUT_A_OUT_B_VAL, val);
+}
+
+static int fpc202_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+ struct fpc202_priv *priv = gpiochip_get_data(chip);
+ u8 reg, bit;
+ int ret;
+
+ if (offset < FPC202_GPIO_P0_S0_IN_B) {
+ reg = FPC202_REG_IN_A_INT;
+ bit = BIT(4 + offset);
+ } else if (offset < FPC202_GPIO_P0_S0_OUT_A) {
+ reg = FPC202_REG_IN_C_IN_B;
+ bit = BIT(offset - FPC202_GPIO_P0_S0_IN_B);
+ } else {
+ reg = FPC202_REG_OUT_A_OUT_B_VAL;
+ bit = BIT(offset - FPC202_GPIO_P0_S0_OUT_A);
+ }
+
+ ret = fpc202_read(priv, reg);
+ if (ret < 0)
+ return ret;
+
+ return !!(((u8)ret) & bit);
+}
+
+static int fpc202_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
+{
+ if (fpc202_gpio_get_dir(offset) == GPIO_LINE_DIRECTION_OUT)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int fpc202_gpio_direction_output(struct gpio_chip *chip, unsigned int offset,
+ int value)
+{
+ struct fpc202_priv *priv = gpiochip_get_data(chip);
+ int ret;
+ u8 val;
+
+ if (fpc202_gpio_get_dir(offset) == GPIO_LINE_DIRECTION_IN)
+ return -EINVAL;
+
+ fpc202_gpio_set(chip, offset, value);
+
+ ret = fpc202_read(priv, FPC202_REG_OUT_A_OUT_B);
+ if (ret < 0)
+ return ret;
+
+ val = (u8)ret | BIT(offset - FPC202_GPIO_P0_S0_OUT_A);
+
+ return fpc202_write(priv, FPC202_REG_OUT_A_OUT_B, val);
+}
+
+/*
+ * Set the translation table entry associated with a port and device number.
+ *
+ * Each downstream port of the FPC202 has two fixed aliases corresponding to
+ * device numbers 0 and 1. If one of these aliases is found in an incoming I2C
+ * transfer, it will be translated to the address given by the corresponding
+ * translation table entry.
+ */
+static int fpc202_write_dev_addr(struct fpc202_priv *priv, u32 port_id, int dev_num, u16 addr)
+{
+ int ret, reg_mod, reg_aux;
+ u8 val;
+
+ mutex_lock(&priv->reg_dev_lock);
+
+ reg_mod = FPC202_REG_MOD_DEV(port_id, dev_num);
+ reg_aux = FPC202_REG_AUX_DEV(port_id, dev_num);
+ val = addr & 0x7f;
+
+ ret = fpc202_write(priv, reg_mod, val);
+ if (ret)
+ goto out_unlock;
+
+ /*
+ * The FPC202 datasheet is unclear about the role of the AUX registers.
+ * Empirically, writing to them as well seems to be necessary for
+ * address translation to function properly.
+ */
+ ret = fpc202_write(priv, reg_aux, val);
+
+ priv->addr_caches[port_id][dev_num] = val;
+
+out_unlock:
+ mutex_unlock(&priv->reg_dev_lock);
+ return ret;
+}
+
+static int fpc202_attach_addr(struct i2c_atr *atr, u32 chan_id,
+ u16 addr, u16 alias)
+{
+ struct fpc202_priv *priv = i2c_atr_get_driver_data(atr);
+
+ dev_dbg(&priv->client->dev, "attaching address 0x%02x to alias 0x%02x\n", addr, alias);
+
+ return fpc202_write_dev_addr(priv, chan_id, fpc202_dev_num_from_alias(alias), addr);
+}
+
+static void fpc202_detach_addr(struct i2c_atr *atr, u32 chan_id,
+ u16 addr)
+{
+ struct fpc202_priv *priv = i2c_atr_get_driver_data(atr);
+ int dev_num, reg_mod, val;
+
+ for (dev_num = 0; dev_num < 2; dev_num++) {
+ reg_mod = FPC202_REG_MOD_DEV(chan_id, dev_num);
+
+ mutex_lock(&priv->reg_dev_lock);
+
+ val = priv->addr_caches[chan_id][dev_num];
+
+ mutex_unlock(&priv->reg_dev_lock);
+
+ if (val < 0) {
+ dev_err(&priv->client->dev, "failed to read register 0x%x while detaching address 0x%02x\n",
+ reg_mod, addr);
+ return;
+ }
+
+ if (val == (addr & 0x7f)) {
+ fpc202_write_dev_addr(priv, chan_id, dev_num, FPC202_REG_DEV_INVALID);
+ return;
+ }
+ }
+}
+
+struct i2c_atr_ops fpc202_atr_ops = {
+ .attach_addr = fpc202_attach_addr,
+ .detach_addr = fpc202_detach_addr,
+};
+
+static int fpc202_probe_port(struct fpc202_priv *priv, int port_id)
+{
+ struct device *dev = &priv->client->dev;
+ u16 aliases[FPC202_ALIASES_PER_PORT] = { };
+ struct i2c_atr_adap_desc desc = { };
+ struct device_node *i2c_handle;
+ char port_name[6];
+ int ret = 0;
+
+ if (port_id > 2)
+ return -EINVAL;
+
+ snprintf(port_name, 6, "port%d", port_id);
+
+ i2c_handle = of_get_child_by_name(dev->of_node, port_name);
+ if (!i2c_handle)
+ return -EINVAL;
+
+ desc.chan_id = port_id;
+ desc.parent = dev;
+ desc.bus_handle = of_node_to_fwnode(i2c_handle);
+ desc.num_aliases = FPC202_ALIASES_PER_PORT;
+
+ fpc202_fill_alias_table(priv->client, aliases, port_id);
+ desc.aliases = aliases;
+
+ ret = i2c_atr_add_adapter(priv->atr, &desc);
+ if (ret)
+ return ret;
+
+ of_node_put(i2c_handle);
+
+ ret = fpc202_write_dev_addr(priv, port_id, 0, FPC202_REG_DEV_INVALID);
+ if (ret)
+ return ret;
+
+ return fpc202_write_dev_addr(priv, port_id, 1, FPC202_REG_DEV_INVALID);
+}
+
+static int fpc202_probe(struct i2c_client *client)
+{
+ struct device *dev = &client->dev;
+ struct fpc202_priv *priv;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ mutex_init(&priv->reg_dev_lock);
+
+ priv->client = client;
+ i2c_set_clientdata(client, priv);
+
+ priv->en_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_HIGH);
+ if (IS_ERR(priv->en_gpio)) {
+ ret = PTR_ERR(priv->en_gpio);
+ dev_err(dev, "failed to fetch enable GPIO! err %d\n", ret);
+ goto destroy_mutex;
+ }
+
+ priv->gpio.label = "gpio-fpc202";
+ priv->gpio.base = -1;
+ priv->gpio.direction_input = fpc202_gpio_direction_input;
+ priv->gpio.direction_output = fpc202_gpio_direction_output;
+ priv->gpio.set = fpc202_gpio_set;
+ priv->gpio.get = fpc202_gpio_get;
+ priv->gpio.ngpio = FPC202_GPIO_COUNT;
+ priv->gpio.parent = dev;
+ priv->gpio.owner = THIS_MODULE;
+
+ ret = gpiochip_add_data(&priv->gpio, priv);
+ if (ret) {
+ priv->gpio.parent = NULL;
+ dev_err(dev, "failed to add gpiochip err %d", ret);
+ goto disable_gpio;
+ }
+
+ priv->atr = i2c_atr_new(client->adapter, dev, &fpc202_atr_ops, 2, I2C_ATR_FLAG_DYNAMIC_C2A);
+ if (IS_ERR(priv->atr)) {
+ ret = PTR_ERR(priv->atr);
+ dev_err(dev, "failed to create i2c atr err %d", ret);
+ goto disable_gpio;
+ }
+
+ i2c_atr_set_driver_data(priv->atr, priv);
+
+ ret = fpc202_probe_port(priv, 0);
+ if (ret) {
+ dev_err(dev, "Failed to probe port 0, err %d\n", ret);
+ goto delete_atr;
+ }
+
+ ret = fpc202_probe_port(priv, 1);
+ if (ret) {
+ dev_err(dev, "Failed to probe port 1, err %d\n", ret);
+ goto delete_atr;
+ }
+
+ dev_info(&client->dev, "%s FPC202 Dual Port controller found\n", client->name);
+
+ goto out;
+
+delete_atr:
+ i2c_atr_delete(priv->atr);
+disable_gpio:
+ fpc202_set_enable(priv, 0);
+ gpiochip_remove(&priv->gpio);
+destroy_mutex:
+ mutex_destroy(&priv->reg_dev_lock);
+out:
+ return ret;
+}
+
+static void fpc202_remove(struct i2c_client *client)
+{
+ struct fpc202_priv *priv = i2c_get_clientdata(client);
+
+ mutex_destroy(&priv->reg_dev_lock);
+
+ i2c_atr_delete(priv->atr);
+
+ fpc202_set_enable(priv, 0);
+ gpiochip_remove(&priv->gpio);
+}
+
+static const struct of_device_id fpc202_of_match[] = {
+ { .compatible = "ti,fpc202" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, fpc202_of_match);
+
+static struct i2c_driver fpc202_driver = {
+ .driver = {
+ .name = "fpc202",
+ .of_match_table = fpc202_of_match,
+ },
+ .probe = fpc202_probe,
+ .remove = fpc202_remove,
+};
+
+module_i2c_driver(fpc202_driver);
+
+MODULE_AUTHOR("Romain Gantois <romain.gantois@bootlin.com>");
+MODULE_DESCRIPTION("TI FPC202 Dual Port Controller driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(I2C_ATR);

--
2.47.0