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Date: Tue, 9 Aug 2022 10:06:35 -0700
From: Russ Weight <russell.h.weight@...el.com>
To: Tianfei Zhang <tianfei.zhang@...el.com>, <broonie@...nel.org>,
<gregkh@...uxfoundation.org>, <rafael@...nel.org>,
<linux-kernel@...r.kernel.org>
CC: <hao.wu@...el.com>, <trix@...hat.com>, <yilun.xu@...el.com>,
"Matthew Gerlach" <matthew.gerlach@...ux.intel.com>
Subject: Re: [PATCH v1] regmap: add generic indirect regmap support
On 6/6/22 18:37, Tianfei Zhang wrote:
> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>
> This patch adds support for regmap APIs that are intended to be used by
> the drivers of some devices which support generic indirect register access,
> for example PMCI (Platform Management Control Interface) device, HSSI
> (High Speed Serial Interface) device in FPGA.
>
> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
> Signed-off-by: Tianfei Zhang <tianfei.zhang@...el.com>
> ---
> drivers/base/regmap/Kconfig | 3 +
> drivers/base/regmap/Makefile | 1 +
> .../base/regmap/regmap-indirect-register.c | 133 ++++++++++++++++++
> include/linux/regmap.h | 12 ++
> 4 files changed, 149 insertions(+)
> create mode 100644 drivers/base/regmap/regmap-indirect-register.c
>
> diff --git a/drivers/base/regmap/Kconfig b/drivers/base/regmap/Kconfig
> index 159bac6c5046..4ea590604f8d 100644
> --- a/drivers/base/regmap/Kconfig
> +++ b/drivers/base/regmap/Kconfig
> @@ -65,3 +65,6 @@ config REGMAP_I3C
> config REGMAP_SPI_AVMM
> tristate
> depends on SPI
> +
> +config REGMAP_INDIRECT_REGISTER
> + tristate
> diff --git a/drivers/base/regmap/Makefile b/drivers/base/regmap/Makefile
> index 11facb32a027..504a32b79d8c 100644
> --- a/drivers/base/regmap/Makefile
> +++ b/drivers/base/regmap/Makefile
> @@ -20,3 +20,4 @@ obj-$(CONFIG_REGMAP_SCCB) += regmap-sccb.o
> obj-$(CONFIG_REGMAP_I3C) += regmap-i3c.o
> obj-$(CONFIG_REGMAP_SPI_AVMM) += regmap-spi-avmm.o
> obj-$(CONFIG_REGMAP_MDIO) += regmap-mdio.o
> +obj-$(CONFIG_REGMAP_INDIRECT_REGISTER) += regmap-indirect-register.o
> diff --git a/drivers/base/regmap/regmap-indirect-register.c b/drivers/base/regmap/regmap-indirect-register.c
> new file mode 100644
> index 000000000000..0b748e48bd87
> --- /dev/null
> +++ b/drivers/base/regmap/regmap-indirect-register.c
> @@ -0,0 +1,133 @@
> +// SPDX-License-Identifier: GPL-2.0
> +//
> +// Indirect Register Access.
> +//
> +// Copyright (C) 2022 Intel Corporation, Inc.
> +
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#define INDIRECT_CMD_OFF 0x0
> +#define INDIRECT_CMD_RD BIT(0)
> +#define INDIRECT_CMD_WR BIT(1)
> +#define INDIRECT_CMD_ACK BIT(2)
> +
> +#define INDIRECT_ADDR_OFF 0x4
> +#define INDIRECT_RD_OFF 0x8
> +#define INDIRECT_WR_OFF 0xc
> +
> +#define INDIRECT_INT_US 1
> +#define INDIRECT_TIMEOUT_US 10000
> +
> +struct indirect_ctx {
> + void __iomem *base;
> + struct device *dev;
> +};
> +
> +static int indirect_bus_clr_cmd(struct indirect_ctx *ctx)
> +{
> + unsigned int cmd;
> + int ret;
> +
> + writel(0, ctx->base + INDIRECT_CMD_OFF);
> + ret = readl_poll_timeout((ctx->base + INDIRECT_CMD_OFF), cmd,
> + (!cmd), INDIRECT_INT_US, INDIRECT_TIMEOUT_US);
> + if (ret)
> + dev_err(ctx->dev, "%s timed out on clearing cmd 0x%xn", __func__, cmd);
The line-return in the above dev_err() is missing a forward slash: \n
- Russ
> +
> + return ret;
> +}
> +
> +static int indirect_bus_reg_read(void *context, unsigned int reg,
> + unsigned int *val)
> +{
> + struct indirect_ctx *ctx = context;
> + unsigned int cmd;
> + int ret;
> +
> + cmd = readl(ctx->base + INDIRECT_CMD_OFF);
> + if (cmd)
> + dev_warn(ctx->dev, "%s non-zero cmd 0x%x\n", __func__, cmd);
> +
> + writel(reg, ctx->base + INDIRECT_ADDR_OFF);
> + writel(INDIRECT_CMD_RD, ctx->base + INDIRECT_CMD_OFF);
> + ret = readl_poll_timeout((ctx->base + INDIRECT_CMD_OFF), cmd,
> + (cmd & INDIRECT_CMD_ACK), INDIRECT_INT_US,
> + INDIRECT_TIMEOUT_US);
> + if (ret) {
> + dev_err(ctx->dev, "%s timed out on reg 0x%x cmd 0x%x\n", __func__, reg, cmd);
> + goto out;
> + }
> +
> + *val = readl(ctx->base + INDIRECT_RD_OFF);
> +
> + if (indirect_bus_clr_cmd(ctx))
> + ret = -ETIMEDOUT;
> +
> +out:
> + return ret;
> +}
> +
> +static int indirect_bus_reg_write(void *context, unsigned int reg,
> + unsigned int val)
> +{
> + struct indirect_ctx *ctx = context;
> + unsigned int cmd;
> + int ret;
> +
> + cmd = readl(ctx->base + INDIRECT_CMD_OFF);
> + if (cmd)
> + dev_warn(ctx->dev, "%s non-zero cmd 0x%x\n", __func__, cmd);
> +
> + writel(val, ctx->base + INDIRECT_WR_OFF);
> + writel(reg, ctx->base + INDIRECT_ADDR_OFF);
> + writel(INDIRECT_CMD_WR, ctx->base + INDIRECT_CMD_OFF);
> + ret = readl_poll_timeout((ctx->base + INDIRECT_CMD_OFF), cmd,
> + (cmd & INDIRECT_CMD_ACK), INDIRECT_INT_US,
> + INDIRECT_TIMEOUT_US);
> + if (ret) {
> + dev_err(ctx->dev, "%s timed out on reg 0x%x cmd 0x%x\n", __func__, reg, cmd);
> + goto out;
> + }
> +
> + if (indirect_bus_clr_cmd(ctx))
> + ret = -ETIMEDOUT;
> +
> +out:
> + return ret;
> +}
> +
> +static const struct regmap_bus indirect_bus = {
> + .reg_write = indirect_bus_reg_write,
> + .reg_read = indirect_bus_reg_read,
> +};
> +
> +/**
> + * devm_regmap_init_indirect_register - create a regmap for indirect register access
> + * @dev: device creating the regmap
> + * @base: __iomem point to base of memory with mailbox
> + * @cfg: regmap_config describing interface
> + *
> + * Return: 0 on success, negative error code otherwise.
> + */
> +struct regmap *devm_regmap_init_indirect_register(struct device *dev,
> + void __iomem *base,
> + struct regmap_config *cfg)
> +{
> + struct indirect_ctx *ctx;
> +
> + ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
> + if (!ctx)
> + return NULL;
> +
> + ctx->base = base;
> + ctx->dev = dev;
> +
> + return devm_regmap_init(dev, &indirect_bus, ctx, cfg);
> +}
> +EXPORT_SYMBOL_GPL(devm_regmap_init_indirect_register);
> +
> +MODULE_DESCRIPTION("Indirect Register Access");
> +MODULE_AUTHOR("Intel Corporation");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/regmap.h b/include/linux/regmap.h
> index de81a94d7b30..72eb38883e88 100644
> --- a/include/linux/regmap.h
> +++ b/include/linux/regmap.h
> @@ -670,6 +670,18 @@ struct regmap *__devm_regmap_init_spi_avmm(struct spi_device *spi,
> const struct regmap_config *config,
> struct lock_class_key *lock_key,
> const char *lock_name);
> +/**
> + * devm_regmap_init_indirect_register - create a regmap for indirect register access
> + * @dev: device creating the regmap
> + * @base: __iomem point to base of memory with mailbox
> + * @cfg: regmap_config describing interface
> + *
> + * Return: 0 on success, negative error code otherwise.
> + */
> +struct regmap *devm_regmap_init_indirect_register(struct device *dev,
> + void __iomem *base,
> + struct regmap_config *cfg);
> +
> /*
> * Wrapper for regmap_init macros to include a unique lockdep key and name
> * for each call. No-op if CONFIG_LOCKDEP is not set.
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