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Date: Mon, 28 Sep 2015 20:23:02 +0200
From: Marcel Holtmann <marcel@...tmann.org>
To: Loic Poulain <loic.poulain@...el.com>
Cc: broonie@...nel.org, linux-bluetooth@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] regmap: Add HCI iBT support
Hi Loic,
I would try to use a bit more descriptive subject line here. Maybe something along the lines of add iBT register access over HCI support.
> Add support for Intel Bluetooth silicon register access over HCI.
> Intel BT/FM combo chip allows to read/write some registers (e.g. FM
> registers) via its HCI interface.
>
> Read/Write operations are performed via a HCI transaction composed of
> a HCI command (host->controller) followed by a HCI command complete
> event (controller->host). Read/Write Command opcodes can be specified
> to the regmap init function.
> We define data formats which are intel/vendor specific.
>
> Register Read/Write HCI command payload (Host):
> Field: | REG ADDR | MODE | DATA_LEN | DATA... |
> size: | 32b | 8b | 8b | 8b* |
>
> Register Read HCI command complete event payload (Controller):
> Field: | CMD STATUS | REG ADDR | DATA... |
> size: | 8b | 32b | 8b* |
>
> Register Write HCI command complete event payload (Controller):
> Field: | CMD_STATUS |
> size: | 8b |
>
> Since this payload is HCI encapsulated, Little Endian byte order is
> used.
>
> Write/Read Example:
>
> If we write 0x0000002a at address 0x00008c04, with opcode_write 0xfc5d,
> The resulting transaction is (btmon trace):
>
> < HCI Command (0x3f|0x005d) plen 10 [hci0]
> 04 8c 00 00 02 04 2a 00 00 00
>> HCI Event (0x0e) plen 4
> Unknown (0x3f|0x005d) ncmd 1
> 00
>
> Then, if we read the same register with opcode_read 0xfc5e:
>
> < HCI Command (0x3f|0x005e) plen 6 [hci0]
> 04 8c 00 00 02 04
>> HCI Event (0x0e) plen 12 [hci0]
> Unknown (0x3f|0x005e) ncmd 1
> 00 04 8c 00 00 2a 00 00 00
>
> Signed-off-by: Loic Poulain <loic.poulain@...el.com>
> ---
> v2: Change "hci" to "ibt" since it's intel specific
> Add comments for clarification
> Remove unjustified default opcodes
> Protect __hci_cmd_sync call with hdev req_lock
> Replace BUG_ON with WARN_ONCE
>
> drivers/base/regmap/Kconfig | 6 +-
> drivers/base/regmap/Makefile | 1 +
> drivers/base/regmap/regmap-ibt.c | 283 +++++++++++++++++++++++++++++++++++++++
> include/linux/regmap.h | 7 +
> 4 files changed, 296 insertions(+), 1 deletion(-)
> create mode 100644 drivers/base/regmap/regmap-ibt.c
>
> diff --git a/drivers/base/regmap/Kconfig b/drivers/base/regmap/Kconfig
> index db9d00c3..e34675f 100644
> --- a/drivers/base/regmap/Kconfig
> +++ b/drivers/base/regmap/Kconfig
> @@ -3,7 +3,7 @@
> # subsystems should select the appropriate symbols.
>
> config REGMAP
> - default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ)
> + default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ || REGMAP_IBT)
> select LZO_COMPRESS
> select LZO_DECOMPRESS
> select IRQ_DOMAIN if REGMAP_IRQ
> @@ -29,3 +29,7 @@ config REGMAP_MMIO
>
> config REGMAP_IRQ
> bool
> +
> +config REGMAP_IBT
> + tristate
> + depends on BT
> \ No newline at end of file
> diff --git a/drivers/base/regmap/Makefile b/drivers/base/regmap/Makefile
> index 609e4c8..e7fd73f 100644
> --- a/drivers/base/regmap/Makefile
> +++ b/drivers/base/regmap/Makefile
> @@ -10,3 +10,4 @@ obj-$(CONFIG_REGMAP_SPI) += regmap-spi.o
> obj-$(CONFIG_REGMAP_SPMI) += regmap-spmi.o
> obj-$(CONFIG_REGMAP_MMIO) += regmap-mmio.o
> obj-$(CONFIG_REGMAP_IRQ) += regmap-irq.o
> +obj-$(CONFIG_REGMAP_IBT) += regmap-ibt.o
> diff --git a/drivers/base/regmap/regmap-ibt.c b/drivers/base/regmap/regmap-ibt.c
> new file mode 100644
> index 0000000..feb7607
> --- /dev/null
> +++ b/drivers/base/regmap/regmap-ibt.c
> @@ -0,0 +1,283 @@
> +/*
> + * Register map access API - iBT support
> + *
> + * Copyright 2015 Intel Corporation
> + *
> + * Author: Loic Poulain <loic.poulain@...el.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/regmap.h>
> +#include <linux/module.h>
> +#include <linux/skbuff.h>
> +
> +#include <net/bluetooth/bluetooth.h>
> +#include <net/bluetooth/hci_core.h>
> +
> +#include "internal.h"
> +
> +#define IBT_REG_MODE_8BIT 0x00
> +#define IBT_REG_MODE_16BIT 0x01
> +#define IBT_REG_MODE_32BIT 0x02
> +
> +struct regmap_ibt_context {
> + struct hci_dev *hdev;
> + __u16 op_write;
> + __u16 op_read;
> +};
> +
> +/**
> + * HCI Command payload for register read/write
> + *
> + * @raddr: Register address (32bit only)
> + * @mode: Value access mode (8bit, 16bit, 32bit)
> + * @len: Data len to read/write
> + * @data: Data to write
> + */
> +struct ibt_cp_reg_access {
> + __le32 addr;
> + __u8 mode;
> + __u8 len;
> + __u8 data[0];
> +} __packed;
> +
> +/**
> + * HCI Command Complete Event payload for register read
> + *
> + * @status: cmd read status
> + * @addr: Register address (32bit only)
> + * @data: Register value
> + */
> +struct ibt_rp_reg_access {
> + __u8 status;
> + __le32 addr;
> + __u8 data[0];
> +} __packed;
> +
> +static int regmap_ibt_read(void *context, const void *addr, size_t reg_size,
> + void *val, size_t val_size)
> +{
> + struct regmap_ibt_context *ctx = context;
> + struct ibt_cp_reg_access cp;
> + struct ibt_rp_reg_access *rp;
> + struct sk_buff *skb;
> + int err = 0;
> +
> + if (reg_size != sizeof(__le32))
> + return -EINVAL;
> +
> + switch (val_size) {
> + case 1:
> + cp.mode = IBT_REG_MODE_8BIT;
> + break;
> + case 2:
> + cp.mode = IBT_REG_MODE_16BIT;
> + break;
> + case 4:
> + cp.mode = IBT_REG_MODE_32BIT;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + /* regmap provides a little-endian formatted addr */
> + cp.addr = *(__le32 *)addr;
> + cp.len = val_size;
> +
> + bt_dev_dbg(ctx->hdev, "Register (0x%x) read", le32_to_cpu(cp.addr));
> +
> + mutex_lock(&ctx->hdev->req_lock);
> + skb = __hci_cmd_sync(ctx->hdev, ctx->op_read, sizeof(cp), &cp,
> + HCI_CMD_TIMEOUT);
> + mutex_unlock(&ctx->hdev->req_lock);
I did not realize that hci_req_lock is limited to internal hci_core.c. So I think we should instead introduce an exported function hci_cmd_sync that does exactly the same as __hci_cmd_sync, but takes the request lock.
> +
> + if (IS_ERR(skb)) {
> + bt_dev_err(ctx->hdev, "regmap: Register (0x%x) read error (%ld)",
> + le32_to_cpu(cp.addr), PTR_ERR(skb));
> + return PTR_ERR(skb);
> + }
> +
> + if (skb->len != sizeof(*rp) + val_size) {
> + bt_dev_err(ctx->hdev, "regmap: Register (0x%x) read error, bad len",
> + le32_to_cpu(cp.addr));
> + err = -EINVAL;
> + goto done;
> + }
> +
> + rp = (struct ibt_rp_reg_access *)skb->data;
> +
> + if (rp->addr != cp.addr) {
> + bt_dev_err(ctx->hdev, "regmap: Register (0x%x) read error, bad addr",
> + le32_to_cpu(rp->addr));
> + err = -EINVAL;
> + goto done;
> + }
> +
> + memcpy(val, rp->data, val_size);
> +
> +done:
> + kfree_skb(skb);
> + return err;
> +}
> +
> +static int regmap_ibt_gather_write(void *context,
> + const void *addr, size_t reg_size,
> + const void *val, size_t val_size)
> +{
> + struct regmap_ibt_context *ctx = context;
> + struct ibt_cp_reg_access *cp;
> + struct sk_buff *skb;
> + int plen = sizeof(*cp) + val_size;
> + u8 mode;
> + int err = 0;
> +
> + if (reg_size != sizeof(__le32))
> + return -EINVAL;
> +
> + switch (val_size) {
> + case 1:
> + mode = IBT_REG_MODE_8BIT;
> + break;
> + case 2:
> + mode = IBT_REG_MODE_16BIT;
> + break;
> + case 4:
> + mode = IBT_REG_MODE_32BIT;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + cp = kmalloc(plen, GFP_KERNEL);
> + if (!cp)
> + return -ENOMEM;
> +
> + /* regmap provides a little-endian formatted addr/value */
> + cp->addr = *(__le32 *)addr;
> + cp->mode = mode;
> + cp->len = val_size;
> + memcpy(&cp->data, val, val_size);
> +
> + bt_dev_dbg(ctx->hdev, "Register (0x%x) write", le32_to_cpu(cp->addr));
> +
> + mutex_lock(&ctx->hdev->req_lock);
> + skb = __hci_cmd_sync(ctx->hdev, ctx->op_write, plen, cp,
> + HCI_CMD_TIMEOUT);
> + mutex_unlock(&ctx->hdev->req_lock);
Same as above. I feel better introducing hci_cmd_sync instead of relying on some internal hci_dev lock.
> +
> + if (IS_ERR(skb)) {
> + bt_dev_err(ctx->hdev, "regmap: Register (0x%x) write error (%ld)",
> + le32_to_cpu(cp->addr), PTR_ERR(skb));
> + err = PTR_ERR(skb);
> + goto done;
> + }
> + kfree_skb(skb);
> +
> +done:
> + kfree(cp);
> + return err;
> +}
> +
> +static int regmap_ibt_write(void *context, const void *data, size_t count)
> +{
> + /* data contains register+value, since we only support 32bit addr,
> + * minimum data size is 4 bytes.
> + */
> + if (WARN_ONCE(count < 4, "Invalid register access"))
> + return -EINVAL;
> +
> + return regmap_ibt_gather_write(context, data, 4, data + 4, count - 4);
> +}
> +
> +static void regmap_ibt_free_context(void *context)
> +{
> + kfree(context);
> +}
> +
> +static struct regmap_bus regmap_ibt = {
> + .read = regmap_ibt_read,
> + .write = regmap_ibt_write,
> + .gather_write = regmap_ibt_gather_write,
> + .free_context = regmap_ibt_free_context,
> + .reg_format_endian_default = REGMAP_ENDIAN_LITTLE,
> + .val_format_endian_default = REGMAP_ENDIAN_LITTLE,
> +};
> +
> +static struct regmap *__regmap_init_ibt(struct hci_dev *hdev,
> + u16 opcode_read, u16 opcode_write,
> + const struct regmap_config *config,
> + bool devm)
> +{
> + struct regmap_ibt_context *ctx;
> +
> + if (!config)
> + return ERR_PTR(-EINVAL);
> +
> + bt_dev_info(hdev, "regmap: Init %s-R%x-W%x region", config->name,
> + opcode_read, opcode_write);
> +
> + if (config->reg_bits != 32) {
> + bt_dev_err(hdev, "regmap: Unsupported address size: %d",
> + config->reg_bits);
> + return ERR_PTR(-EINVAL);
> + }
> +
> + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> + if (!ctx)
> + return ERR_PTR(-ENOMEM);
> +
> + ctx->op_read = opcode_read;
> + ctx->op_write = opcode_write;
> + ctx->hdev = hdev;
> +
> + if (devm)
> + return devm_regmap_init(&hdev->dev, ®map_ibt, ctx, config);
> + else
> + return regmap_init(&hdev->dev, ®map_ibt, ctx, config);
> +}
> +
> +/**
> + * regmap_init_ibt(): Initialize register map
> + *
> + * @hdev: HCI Device that will be interacted with
> + * @config: Configuration for register map
> + * @opcode_read: HCI opcode command for register-read operation
> + * @opcode_write: HCI opcode command for register-write operation
> + *
> + * The return value will be an ERR_PTR() on error or a valid pointer to
> + * a struct regmap.
> + */
> +struct regmap *regmap_init_ibt(struct hci_dev *hdev,
> + u16 opcode_read, u16 opcode_write,
> + const struct regmap_config *config)
> +{
> + return __regmap_init_ibt(hdev, opcode_read, opcode_write, config,
> + false);
> +}
> +EXPORT_SYMBOL_GPL(regmap_init_ibt);
> +
> +/**
> + * devm_regmap_init_ibt(): Initialize register map
> + *
> + * @hdev: HCI Device that will be interacted with
> + * @config: Configuration for register map
> + * @opcode_read: HCI opcode command for register-read operation
> + * @opcode_write: HCI opcode command for register-write operation
> + *
> + * The return value will be an ERR_PTR() on error or a valid pointer
> + * to a struct regmap. The regmap will be automatically freed by the
> + * device management code.
> + */
> +struct regmap *devm_regmap_init_ibt(struct hci_dev *hdev,
> + u16 opcode_read, u16 opcode_write,
> + const struct regmap_config *config)
> +{
> + return __regmap_init_ibt(hdev, opcode_read, opcode_write, config,
> + true);
> +}
> +EXPORT_SYMBOL_GPL(devm_regmap_init_ibt);
> +
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/regmap.h b/include/linux/regmap.h
> index 59c55ea..af7c146 100644
> --- a/include/linux/regmap.h
> +++ b/include/linux/regmap.h
> @@ -28,6 +28,7 @@ struct regmap;
> struct regmap_range_cfg;
> struct regmap_field;
> struct snd_ac97;
> +struct hci_dev;
>
> /* An enum of all the supported cache types */
> enum regcache_type {
> @@ -343,6 +344,9 @@ struct regmap *regmap_init_mmio_clk(struct device *dev, const char *clk_id,
> const struct regmap_config *config);
> struct regmap *regmap_init_ac97(struct snd_ac97 *ac97,
> const struct regmap_config *config);
> +struct regmap *regmap_init_ibt(struct hci_dev *hdev,
> + u16 opcode_read, u16 opcode_write,
> + const struct regmap_config *config);
>
> struct regmap *devm_regmap_init(struct device *dev,
> const struct regmap_bus *bus,
> @@ -361,6 +365,9 @@ struct regmap *devm_regmap_init_mmio_clk(struct device *dev, const char *clk_id,
> const struct regmap_config *config);
> struct regmap *devm_regmap_init_ac97(struct snd_ac97 *ac97,
> const struct regmap_config *config);
> +struct regmap *devm_regmap_init_ibt(struct hci_dev *hdev,
> + u16 opcode_read, u16 opcode_write,
> + const struct regmap_config *config);
With the minor modification to introduce hci_cmd_sync first, this looks good to me. However now the question is on how we merge this? I can take this through the bluetooth-next tree, but then I might need some ACK from the regmap maintainers.
Regards
Marcel
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