Chip level TCPC driver for Maxim's TCPCI implementation.
This TCPC implementation does not support the following
commands: COMMAND.SinkVbus, COMMAND.SourceVbusDefaultVoltage,
COMMAND.SourceVbusHighVoltage. Instead the sinking and sourcing
from vbus is supported by writes to custom registers.

Signed-off-by: Badhri Jagan Sridharan <[email protected]>
Reviewed-by: Heikki Krogerus <[email protected]>
---
Changes since v1:
- Changing patch version to v6 to fix version number confusion.
- Removed setting USB_PSY and terminating description with period as
  suggested by Randy.

Changes since v6:
- Addressed Heikki comments:
  - Removed TX discarded message
  - Removed the redundant TCPC_POWER_STATUS_UNINIT check
- Cleaned up irq setup routine

Changes since v7:
- Added reviewed-by: Heikki

Changes since v8:
- None

Changes since v9:
- None
---
 drivers/usb/typec/tcpm/Kconfig       |   6 +
 drivers/usb/typec/tcpm/Makefile      |  15 +-
 drivers/usb/typec/tcpm/tcpci.h       |   1 +
 drivers/usb/typec/tcpm/tcpci_maxim.c | 461 +++++++++++++++++++++++++++
 4 files changed, 476 insertions(+), 7 deletions(-)
 create mode 100644 drivers/usb/typec/tcpm/tcpci_maxim.c

diff --git a/drivers/usb/typec/tcpm/Kconfig b/drivers/usb/typec/tcpm/Kconfig
index 58a64e1bf627..557f392fe24d 100644
--- a/drivers/usb/typec/tcpm/Kconfig
+++ b/drivers/usb/typec/tcpm/Kconfig
@@ -35,6 +35,12 @@ config TYPEC_MT6360
          USB Type-C. It works with Type-C Port Controller Manager
          to provide USB PD and USB Type-C functionalities.
 
+config TYPEC_TCPCI_MAXIM
+       tristate "Maxim TCPCI based Type-C chip driver"
+       help
+         MAXIM TCPCI based Type-C/PD chip driver. Works with
+         with Type-C Port Controller Manager.
+
 endif # TYPEC_TCPCI
 
 config TYPEC_FUSB302
diff --git a/drivers/usb/typec/tcpm/Makefile b/drivers/usb/typec/tcpm/Makefile
index 7592ccb8c526..7d499f3569fd 100644
--- a/drivers/usb/typec/tcpm/Makefile
+++ b/drivers/usb/typec/tcpm/Makefile
@@ -1,8 +1,9 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_TYPEC_TCPM)       += tcpm.o
-obj-$(CONFIG_TYPEC_FUSB302)    += fusb302.o
-obj-$(CONFIG_TYPEC_WCOVE)      += typec_wcove.o
-typec_wcove-y                  := wcove.o
-obj-$(CONFIG_TYPEC_TCPCI)      += tcpci.o
-obj-$(CONFIG_TYPEC_RT1711H)    += tcpci_rt1711h.o
-obj-$(CONFIG_TYPEC_MT6360)     += tcpci_mt6360.o
+obj-$(CONFIG_TYPEC_TCPM)               += tcpm.o
+obj-$(CONFIG_TYPEC_FUSB302)            += fusb302.o
+obj-$(CONFIG_TYPEC_WCOVE)              += typec_wcove.o
+typec_wcove-y                          := wcove.o
+obj-$(CONFIG_TYPEC_TCPCI)              += tcpci.o
+obj-$(CONFIG_TYPEC_RT1711H)            += tcpci_rt1711h.o
+obj-$(CONFIG_TYPEC_MT6360)             += tcpci_mt6360.o
+obj-$(CONFIG_TYPEC_TCPCI_MAXIM)                += tcpci_maxim.o
diff --git a/drivers/usb/typec/tcpm/tcpci.h b/drivers/usb/typec/tcpm/tcpci.h
index 4d441bdf24d5..82f021a82456 100644
--- a/drivers/usb/typec/tcpm/tcpci.h
+++ b/drivers/usb/typec/tcpm/tcpci.h
@@ -109,6 +109,7 @@
 
 #define TCPC_RX_BYTE_CNT               0x30
 #define TCPC_RX_BUF_FRAME_TYPE         0x31
+#define TCPC_RX_BUF_FRAME_TYPE_SOP     0
 #define TCPC_RX_HDR                    0x32
 #define TCPC_RX_DATA                   0x34 /* through 0x4f */
 
diff --git a/drivers/usb/typec/tcpm/tcpci_maxim.c 
b/drivers/usb/typec/tcpm/tcpci_maxim.c
new file mode 100644
index 000000000000..91337ddb4962
--- /dev/null
+++ b/drivers/usb/typec/tcpm/tcpci_maxim.c
@@ -0,0 +1,461 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020, Google LLC
+ *
+ * MAXIM TCPCI based TCPC driver
+ */
+
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/regmap.h>
+#include <linux/usb/pd.h>
+#include <linux/usb/tcpm.h>
+#include <linux/usb/typec.h>
+
+#include "tcpci.h"
+
+#define PD_ACTIVITY_TIMEOUT_MS                         10000
+
+#define TCPC_VENDOR_ALERT                              0x80
+
+#define TCPC_RECEIVE_BUFFER_COUNT_OFFSET               0
+#define TCPC_RECEIVE_BUFFER_FRAME_TYPE_OFFSET          1
+#define TCPC_RECEIVE_BUFFER_RX_BYTE_BUF_OFFSET         2
+
+/*
+ * LongMessage not supported, hence 32 bytes for buf to be read from 
RECEIVE_BUFFER.
+ * DEVICE_CAPABILITIES_2.LongMessage = 0, the value in READABLE_BYTE_COUNT reg 
shall be
+ * less than or equal to 31. Since, RECEIVE_BUFFER len = 31 + 
1(READABLE_BYTE_COUNT).
+ */
+#define TCPC_RECEIVE_BUFFER_LEN                                32
+
+#define MAX_BUCK_BOOST_SID                             0x69
+#define MAX_BUCK_BOOST_OP                              0xb9
+#define MAX_BUCK_BOOST_OFF                             0
+#define MAX_BUCK_BOOST_SOURCE                          0xa
+#define MAX_BUCK_BOOST_SINK                            0x5
+
+struct max_tcpci_chip {
+       struct tcpci_data data;
+       struct tcpci *tcpci;
+       struct device *dev;
+       struct i2c_client *client;
+       struct tcpm_port *port;
+};
+
+static const struct regmap_range max_tcpci_tcpci_range[] = {
+       regmap_reg_range(0x00, 0x95)
+};
+
+const struct regmap_access_table max_tcpci_tcpci_write_table = {
+       .yes_ranges = max_tcpci_tcpci_range,
+       .n_yes_ranges = ARRAY_SIZE(max_tcpci_tcpci_range),
+};
+
+static const struct regmap_config max_tcpci_regmap_config = {
+       .reg_bits = 8,
+       .val_bits = 8,
+       .max_register = 0x95,
+       .wr_table = &max_tcpci_tcpci_write_table,
+};
+
+static struct max_tcpci_chip *tdata_to_max_tcpci(struct tcpci_data *tdata)
+{
+       return container_of(tdata, struct max_tcpci_chip, data);
+}
+
+static int max_tcpci_read16(struct max_tcpci_chip *chip, unsigned int reg, u16 
*val)
+{
+       return regmap_raw_read(chip->data.regmap, reg, val, sizeof(u16));
+}
+
+static int max_tcpci_write16(struct max_tcpci_chip *chip, unsigned int reg, 
u16 val)
+{
+       return regmap_raw_write(chip->data.regmap, reg, &val, sizeof(u16));
+}
+
+static int max_tcpci_read8(struct max_tcpci_chip *chip, unsigned int reg, u8 
*val)
+{
+       return regmap_raw_read(chip->data.regmap, reg, val, sizeof(u8));
+}
+
+static int max_tcpci_write8(struct max_tcpci_chip *chip, unsigned int reg, u8 
val)
+{
+       return regmap_raw_write(chip->data.regmap, reg, &val, sizeof(u8));
+}
+
+static void max_tcpci_init_regs(struct max_tcpci_chip *chip)
+{
+       u16 alert_mask = 0;
+       int ret;
+
+       ret = max_tcpci_write16(chip, TCPC_ALERT, 0xffff);
+       if (ret < 0) {
+               dev_err(chip->dev, "Error writing to TCPC_ALERT ret:%d\n", ret);
+               return;
+       }
+
+       ret = max_tcpci_write16(chip, TCPC_VENDOR_ALERT, 0xffff);
+       if (ret < 0) {
+               dev_err(chip->dev, "Error writing to TCPC_VENDOR_ALERT 
ret:%d\n", ret);
+               return;
+       }
+
+       alert_mask = TCPC_ALERT_TX_SUCCESS | TCPC_ALERT_TX_DISCARDED | 
TCPC_ALERT_TX_FAILED |
+               TCPC_ALERT_RX_HARD_RST | TCPC_ALERT_RX_STATUS | 
TCPC_ALERT_CC_STATUS |
+               TCPC_ALERT_VBUS_DISCNCT | TCPC_ALERT_RX_BUF_OVF | 
TCPC_ALERT_POWER_STATUS;
+
+       ret = max_tcpci_write16(chip, TCPC_ALERT_MASK, alert_mask);
+       if (ret < 0) {
+               dev_err(chip->dev, "Error writing to TCPC_ALERT_MASK ret:%d\n", 
ret);
+               return;
+       }
+
+       /* Enable vbus voltage monitoring and voltage alerts */
+       ret = max_tcpci_write8(chip, TCPC_POWER_CTRL, 0);
+       if (ret < 0) {
+               dev_err(chip->dev, "Error writing to TCPC_POWER_CTRL ret:%d\n", 
ret);
+               return;
+       }
+}
+
+static void process_rx(struct max_tcpci_chip *chip, u16 status)
+{
+       struct pd_message msg;
+       u8 count, frame_type, rx_buf[TCPC_RECEIVE_BUFFER_LEN];
+       int ret, payload_index;
+       u8 *rx_buf_ptr;
+
+       /*
+        * READABLE_BYTE_COUNT: Indicates the number of bytes in the 
RX_BUF_BYTE_x registers
+        * plus one (for the RX_BUF_FRAME_TYPE) Table 4-36.
+        * Read the count and frame type.
+        */
+       ret = regmap_raw_read(chip->data.regmap, TCPC_RX_BYTE_CNT, rx_buf, 2);
+       if (ret < 0) {
+               dev_err(chip->dev, "TCPC_RX_BYTE_CNT read failed ret:%d", ret);
+               return;
+       }
+
+       count = rx_buf[TCPC_RECEIVE_BUFFER_COUNT_OFFSET];
+       frame_type = rx_buf[TCPC_RECEIVE_BUFFER_FRAME_TYPE_OFFSET];
+
+       if (count == 0 || frame_type != TCPC_RX_BUF_FRAME_TYPE_SOP) {
+               max_tcpci_write16(chip, TCPC_ALERT, TCPC_ALERT_RX_STATUS);
+               dev_err(chip->dev, "%s", count ==  0 ? "error: count is 0" :
+                       "error frame_type is not SOP");
+               return;
+       }
+
+       if (count > sizeof(struct pd_message) || count + 1 > 
TCPC_RECEIVE_BUFFER_LEN) {
+               dev_err(chip->dev, "Invalid TCPC_RX_BYTE_CNT %d", count);
+               return;
+       }
+
+       /*
+        * Read count + 1 as RX_BUF_BYTE_x is hidden and can only be read 
through
+        * TCPC_RX_BYTE_CNT
+        */
+       count += 1;
+       ret = regmap_raw_read(chip->data.regmap, TCPC_RX_BYTE_CNT, rx_buf, 
count);
+       if (ret < 0) {
+               dev_err(chip->dev, "Error: TCPC_RX_BYTE_CNT read failed: %d", 
ret);
+               return;
+       }
+
+       rx_buf_ptr = rx_buf + TCPC_RECEIVE_BUFFER_RX_BYTE_BUF_OFFSET;
+       msg.header = cpu_to_le16(*(u16 *)rx_buf_ptr);
+       rx_buf_ptr = rx_buf_ptr + sizeof(msg.header);
+       for (payload_index = 0; payload_index < pd_header_cnt_le(msg.header); 
payload_index++,
+            rx_buf_ptr += sizeof(msg.payload[0]))
+               msg.payload[payload_index] = cpu_to_le32(*(u32 *)rx_buf_ptr);
+
+       /*
+        * Read complete, clear RX status alert bit.
+        * Clear overflow as well if set.
+        */
+       ret = max_tcpci_write16(chip, TCPC_ALERT, status & 
TCPC_ALERT_RX_BUF_OVF ?
+                               TCPC_ALERT_RX_STATUS | TCPC_ALERT_RX_BUF_OVF :
+                               TCPC_ALERT_RX_STATUS);
+       if (ret < 0)
+               return;
+
+       tcpm_pd_receive(chip->port, &msg);
+}
+
+static int max_tcpci_set_vbus(struct tcpci *tcpci, struct tcpci_data *tdata, 
bool source, bool sink)
+{
+       struct max_tcpci_chip *chip = tdata_to_max_tcpci(tdata);
+       u8 buffer_source[2] = {MAX_BUCK_BOOST_OP, MAX_BUCK_BOOST_SOURCE};
+       u8 buffer_sink[2] = {MAX_BUCK_BOOST_OP, MAX_BUCK_BOOST_SINK};
+       u8 buffer_none[2] = {MAX_BUCK_BOOST_OP, MAX_BUCK_BOOST_OFF};
+       struct i2c_client *i2c = chip->client;
+       int ret;
+
+       struct i2c_msg msgs[] = {
+               {
+                       .addr = MAX_BUCK_BOOST_SID,
+                       .flags = i2c->flags & I2C_M_TEN,
+                       .len = 2,
+                       .buf = source ? buffer_source : sink ? buffer_sink : 
buffer_none,
+               },
+       };
+
+       if (source && sink) {
+               dev_err(chip->dev, "Both source and sink set\n");
+               return -EINVAL;
+       }
+
+       ret = i2c_transfer(i2c->adapter, msgs, 1);
+
+       return  ret < 0 ? ret : 1;
+}
+
+static void process_power_status(struct max_tcpci_chip *chip)
+{
+       u8 pwr_status;
+       int ret;
+
+       ret = max_tcpci_read8(chip, TCPC_POWER_STATUS, &pwr_status);
+       if (ret < 0)
+               return;
+
+       if (pwr_status == 0xff)
+               max_tcpci_init_regs(chip);
+       else
+               tcpm_vbus_change(chip->port);
+}
+
+static void process_tx(struct max_tcpci_chip *chip, u16 status)
+{
+       if (status & TCPC_ALERT_TX_SUCCESS)
+               tcpm_pd_transmit_complete(chip->port, TCPC_TX_SUCCESS);
+       else if (status & TCPC_ALERT_TX_DISCARDED)
+               tcpm_pd_transmit_complete(chip->port, TCPC_TX_DISCARDED);
+       else if (status & TCPC_ALERT_TX_FAILED)
+               tcpm_pd_transmit_complete(chip->port, TCPC_TX_FAILED);
+
+       /* Reinit regs as Hard reset sets them to default value */
+       if ((status & TCPC_ALERT_TX_SUCCESS) && (status & TCPC_ALERT_TX_FAILED))
+               max_tcpci_init_regs(chip);
+}
+
+static irqreturn_t _max_tcpci_irq(struct max_tcpci_chip *chip, u16 status)
+{
+       u16 mask;
+       int ret;
+
+       /*
+        * Clear alert status for everything except RX_STATUS, which shouldn't
+        * be cleared until we have successfully retrieved message.
+        */
+       if (status & ~TCPC_ALERT_RX_STATUS) {
+               mask = status & TCPC_ALERT_RX_BUF_OVF ?
+                       status & ~(TCPC_ALERT_RX_STATUS | 
TCPC_ALERT_RX_BUF_OVF) :
+                       status & ~TCPC_ALERT_RX_STATUS;
+               ret = max_tcpci_write16(chip, TCPC_ALERT, mask);
+               if (ret < 0) {
+                       dev_err(chip->dev, "ALERT clear failed\n");
+                       return ret;
+               }
+       }
+
+       if (status & TCPC_ALERT_RX_BUF_OVF && !(status & TCPC_ALERT_RX_STATUS)) 
{
+               ret = max_tcpci_write16(chip, TCPC_ALERT, (TCPC_ALERT_RX_STATUS 
|
+                                                         
TCPC_ALERT_RX_BUF_OVF));
+               if (ret < 0) {
+                       dev_err(chip->dev, "ALERT clear failed\n");
+                       return ret;
+               }
+       }
+
+       if (status & TCPC_ALERT_RX_STATUS)
+               process_rx(chip, status);
+
+       if (status & TCPC_ALERT_VBUS_DISCNCT)
+               tcpm_vbus_change(chip->port);
+
+       if (status & TCPC_ALERT_CC_STATUS)
+               tcpm_cc_change(chip->port);
+
+       if (status & TCPC_ALERT_POWER_STATUS)
+               process_power_status(chip);
+
+       if (status & TCPC_ALERT_RX_HARD_RST) {
+               tcpm_pd_hard_reset(chip->port);
+               max_tcpci_init_regs(chip);
+       }
+
+       if (status & TCPC_ALERT_TX_SUCCESS || status & TCPC_ALERT_TX_DISCARDED 
|| status &
+           TCPC_ALERT_TX_FAILED)
+               process_tx(chip, status);
+
+       return IRQ_HANDLED;
+}
+
+static irqreturn_t max_tcpci_irq(int irq, void *dev_id)
+{
+       struct max_tcpci_chip *chip = dev_id;
+       u16 status;
+       irqreturn_t irq_return;
+       int ret;
+
+       if (!chip->port)
+               return IRQ_HANDLED;
+
+       ret = max_tcpci_read16(chip, TCPC_ALERT, &status);
+       if (ret < 0) {
+               dev_err(chip->dev, "ALERT read failed\n");
+               return ret;
+       }
+       while (status) {
+               irq_return = _max_tcpci_irq(chip, status);
+               /* Do not return if the ALERT is already set. */
+               ret = max_tcpci_read16(chip, TCPC_ALERT, &status);
+               if (ret < 0)
+                       break;
+       }
+
+       return irq_return;
+}
+
+static irqreturn_t max_tcpci_isr(int irq, void *dev_id)
+{
+       struct max_tcpci_chip *chip = dev_id;
+
+       pm_wakeup_event(chip->dev, PD_ACTIVITY_TIMEOUT_MS);
+
+       if (!chip->port)
+               return IRQ_HANDLED;
+
+       return IRQ_WAKE_THREAD;
+}
+
+static int max_tcpci_init_alert(struct max_tcpci_chip *chip, struct i2c_client 
*client)
+{
+       int ret;
+
+       ret = devm_request_threaded_irq(chip->dev, client->irq, max_tcpci_isr, 
max_tcpci_irq,
+                                       (IRQF_TRIGGER_LOW | IRQF_ONESHOT), 
dev_name(chip->dev),
+                                       chip);
+
+       if (ret < 0)
+               return ret;
+
+       enable_irq_wake(client->irq);
+       return 0;
+}
+
+static int max_tcpci_start_toggling(struct tcpci *tcpci, struct tcpci_data 
*tdata,
+                                   enum typec_cc_status cc)
+{
+       struct max_tcpci_chip *chip = tdata_to_max_tcpci(tdata);
+
+       max_tcpci_init_regs(chip);
+
+       return 0;
+}
+
+static int tcpci_init(struct tcpci *tcpci, struct tcpci_data *data)
+{
+       /*
+        * Generic TCPCI overwrites the regs once this driver initializes
+        * them. Prevent this by returning -1.
+        */
+       return -1;
+}
+
+static int max_tcpci_probe(struct i2c_client *client, const struct 
i2c_device_id *i2c_id)
+{
+       int ret;
+       struct max_tcpci_chip *chip;
+       u8 power_status;
+
+       chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
+       if (!chip)
+               return -ENOMEM;
+
+       chip->client = client;
+       chip->data.regmap = devm_regmap_init_i2c(client, 
&max_tcpci_regmap_config);
+       if (IS_ERR(chip->data.regmap)) {
+               dev_err(&client->dev, "Regmap init failed\n");
+               return PTR_ERR(chip->data.regmap);
+       }
+
+       chip->dev = &client->dev;
+       i2c_set_clientdata(client, chip);
+
+       ret = max_tcpci_read8(chip, TCPC_POWER_STATUS, &power_status);
+       if (ret < 0)
+               return ret;
+
+       /* Chip level tcpci callbacks */
+       chip->data.set_vbus = max_tcpci_set_vbus;
+       chip->data.start_drp_toggling = max_tcpci_start_toggling;
+       chip->data.TX_BUF_BYTE_x_hidden = true;
+       chip->data.init = tcpci_init;
+
+       max_tcpci_init_regs(chip);
+       chip->tcpci = tcpci_register_port(chip->dev, &chip->data);
+       if (IS_ERR_OR_NULL(chip->tcpci)) {
+               dev_err(&client->dev, "TCPCI port registration failed");
+               ret = PTR_ERR(chip->tcpci);
+               return PTR_ERR(chip->tcpci);
+       }
+       chip->port = tcpci_get_tcpm_port(chip->tcpci);
+       ret = max_tcpci_init_alert(chip, client);
+       if (ret < 0)
+               goto unreg_port;
+
+       device_init_wakeup(chip->dev, true);
+       return 0;
+
+unreg_port:
+       tcpci_unregister_port(chip->tcpci);
+
+       return ret;
+}
+
+static int max_tcpci_remove(struct i2c_client *client)
+{
+       struct max_tcpci_chip *chip = i2c_get_clientdata(client);
+
+       if (!IS_ERR_OR_NULL(chip->tcpci))
+               tcpci_unregister_port(chip->tcpci);
+
+       return 0;
+}
+
+static const struct i2c_device_id max_tcpci_id[] = {
+       { "maxtcpc", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, max_tcpci_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id max_tcpci_of_match[] = {
+       { .compatible = "maxim,tcpc", },
+       {},
+};
+MODULE_DEVICE_TABLE(of, max_tcpci_of_match);
+#endif
+
+static struct i2c_driver max_tcpci_i2c_driver = {
+       .driver = {
+               .name = "maxtcpc",
+               .of_match_table = of_match_ptr(max_tcpci_of_match),
+       },
+       .probe = max_tcpci_probe,
+       .remove = max_tcpci_remove,
+       .id_table = max_tcpci_id,
+};
+module_i2c_driver(max_tcpci_i2c_driver);
+
+MODULE_AUTHOR("Badhri Jagan Sridharan <[email protected]>");
+MODULE_DESCRIPTION("Maxim TCPCI based USB Type-C Port Controller Interface 
Driver");
+MODULE_LICENSE("GPL v2");
-- 
2.28.0.806.g8561365e88-goog

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