bif: Add BIF core framework driver
Add a BIF framework which implements core features of the MIPI
(Mobile Industry Processor Interace) BIF (Battery Interface)
specification. MIPI-BIF defines an interface which can be used
to communicate with smart battery packs.
BIF controller drivers register with the BIF framework and
implement hardware specific features. BIF consumers can make use
of an extensive API to communicate with BIF slaves present on a
BIF bus.
Change-Id: Id640344aadf878a49e93b12b16a5ecb181dd5aeb
Signed-off-by: David Collins <collinsd@codeaurora.org>
diff --git a/include/linux/bif/driver.h b/include/linux/bif/driver.h
new file mode 100644
index 0000000..184d46f
--- /dev/null
+++ b/include/linux/bif/driver.h
@@ -0,0 +1,161 @@
+/* Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _LINUX_BIF_DRIVER_H_
+#define _LINUX_BIF_DRIVER_H_
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/types.h>
+#include <linux/bif/consumer.h>
+
+/**
+ * struct bif_ctrl_dev - opaque handle used to identify a given BIF controller
+ * device
+ */
+struct bif_ctrl_dev;
+
+/**
+ * struct bif_ctrl_ops - BIF operations which may be implemented by BIF
+ * controller drivers
+ * @bus_transaction: Perform the specified BIF transaction which does
+ * not result in any slave response.
+ * @bus_transaction_query: Perform the specified BIF transaction which
+ * expects a BQ response in the case of slave
+ * positive acknowledgement.
+ * @bus_transaction_read: Perform the specified BIF transaction which
+ * expects an RD or TACK response from the selected
+ * slave.
+ * @read_slave_registers: Perform all BIF transactions necessary to read
+ * the specified set of contiguous registers from
+ * the previously selected slave. This operation
+ * is used to optimize the common case of slave
+ * register reads since the a BIF controller driver
+ * can take advantage of BIF burst reads while the
+ * BIF core driver cannot due to the inherient
+ * tight timing requirements.
+ * @write_slave_registers: Perform all BIF transactions necessary to write
+ * the specified set of contiguous registers to
+ * the previously selected slave. This operation
+ * is used to optimize the common case of slave
+ * register writes since the a BIF controller
+ * driver can remove redundant steps when
+ * performing several WD commands in a row.
+ * @get_bus_period: Return the tau_bif BIF bus clock period in
+ * nanoseconds.
+ * @set_bus_period: Set the tau_bif BIF bus clock period in
+ * nanoseconds. If the exact period is not
+ * supported by the BIF controller hardware, then
+ * the next larger supported period should be used.
+ * @get_battery_presence: Return the current state of the battery pack.
+ * If a battery pack is present, then return >= 1.
+ * If a battery pack is not present, then return 0.
+ * If an error occurs during presence detection,
+ * then return errno.
+ * @get_battery_rid: Return the measured value of the Rid battery
+ * pack pull-down resistor in ohms.
+ * @get_bus_state: Return the current bus state as defined by one
+ * of the enum bif_bus_state values.
+ * @set_bus_state: Set the BIF bus state to the specified enum
+ * bif_bus_state value.
+ *
+ * The following operations must be defined by every BIF controller driver in
+ * order to ensure baseline functionality:
+ * bus_transaction, bus_transaction_query, get_bus_state, and set_bus_state.
+ *
+ * The BIF core driver is unaware of BIF transaction timing constraints. A
+ * given BIF controller driver must ensure that all timing constraints in the
+ * MIPI-BIF specification are met as transactions are carried out.
+ *
+ * Conversion between 11-bit and 17-bit BIF words (i.e. the insertion of BCF_n,
+ * parity bits, and the inversion bit) must be handled inside of the BIF
+ * controller driver (either in software or hardware). This guarantees maximum
+ * performance if hardware support is available.
+ *
+ * The bus_transaction_read operation must return -ETIMEDOUT in the case of no
+ * RD or TACK word received. This allows the transaction query, TQ, command
+ * to be used for slave selection verification.
+ *
+ * It is acceptable for the BIF bus state to be changed autonomously by a BIF
+ * controller driver in response to low level bus actions without a call to
+ * set_bus_state. One example is the case of receiving a slave interrupt
+ * while in interrupt state as this intrinsically causes the bus to enter the
+ * active communication state.
+ */
+struct bif_ctrl_ops {
+ int (*bus_transaction) (struct bif_ctrl_dev *bdev, int transaction,
+ u8 data);
+ int (*bus_transaction_query) (struct bif_ctrl_dev *bdev,
+ int transaction, u8 data,
+ bool *query_response);
+ int (*bus_transaction_read) (struct bif_ctrl_dev *bdev,
+ int transaction, u8 data,
+ int *response);
+ int (*read_slave_registers) (struct bif_ctrl_dev *bdev, u16 addr,
+ u8 *data, int len);
+ int (*write_slave_registers) (struct bif_ctrl_dev *bdev, u16 addr,
+ const u8 *data, int len);
+ int (*get_bus_period) (struct bif_ctrl_dev *bdev);
+ int (*set_bus_period) (struct bif_ctrl_dev *bdev, int period_ns);
+ int (*get_battery_presence) (struct bif_ctrl_dev *bdev);
+ int (*get_battery_rid) (struct bif_ctrl_dev *bdev);
+ int (*get_bus_state) (struct bif_ctrl_dev *bdev);
+ int (*set_bus_state) (struct bif_ctrl_dev *bdev, int state);
+};
+
+/**
+ * struct bif_ctrl_desc - BIF bus controller descriptor
+ * @name: Name used to identify the BIF controller
+ * @ops: BIF operations supported by the BIF controller
+ * @bus_clock_min_ns: Minimum tau_bif BIF bus clock period supported by the
+ * BIF controller
+ * @bus_clock_max_ns: Maximum tau_bif BIF bus clock period supported by the
+ * BIF controller
+ *
+ * Each BIF controller registered with the BIF core is described with a
+ * structure of this type.
+ */
+struct bif_ctrl_desc {
+ const char *name;
+ struct bif_ctrl_ops *ops;
+ int bus_clock_min_ns;
+ int bus_clock_max_ns;
+};
+
+#ifdef CONFIG_BIF
+
+struct bif_ctrl_dev *bif_ctrl_register(struct bif_ctrl_desc *bif_desc,
+ struct device *dev, void *driver_data, struct device_node *of_node);
+
+void bif_ctrl_unregister(struct bif_ctrl_dev *bdev);
+
+void *bdev_get_drvdata(struct bif_ctrl_dev *bdev);
+
+int bif_ctrl_notify_battery_changed(struct bif_ctrl_dev *bdev);
+int bif_ctrl_notify_slave_irq(struct bif_ctrl_dev *bdev);
+
+#else
+
+static inline struct bif_ctrl_dev *bif_ctrl_register(
+ struct bif_ctrl_desc *bif_desc, struct device *dev, void *driver_data,
+ struct device_node *of_node)
+{ return ERR_PTR(-EINVAL); }
+
+static inline void bif_ctrl_unregister(struct bif_ctrl_dev *bdev) { }
+
+static inline void *bdev_get_drvdata(struct bif_ctrl_dev *bdev) { return NULL; }
+
+int bif_ctrl_notify_slave_irq(struct bif_ctrl_dev *bdev) { return -EINVAL; }
+
+#endif
+
+#endif