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Date: Tue, 16 Jun 2020 19:06:32 +0100
From: Lee Jones <lee.jones@...aro.org>
To: michael@...le.cc, robh+dt@...nel.org, broonie@...nel.org,
gregkh@...uxfoundation.org, andriy.shevchenko@...ux.intel.com,
devicetree@...r.kernel.org, linus.walleij@...aro.org,
bgolaszewski@...libre.com, arnd@...db.de
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] mfd: Add I2C based System Configuaration (SYSCON)
access
On Tue, 16 Jun 2020, Lee Jones wrote:
> The existing SYSCON implementation only supports MMIO (memory mapped)
> accesses, facilitated by Regmap. This extends support for registers
> held behind I2C busses.
>
> Signed-off-by: Lee Jones <lee.jones@...aro.org>
> ---
> drivers/mfd/Kconfig | 7 +++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/syscon-i2c.c | 89 ++++++++++++++++++++++++++++++++++
> include/linux/mfd/syscon-i2c.h | 26 ++++++++++
> 4 files changed, 123 insertions(+)
> create mode 100644 drivers/mfd/syscon-i2c.c
> create mode 100644 include/linux/mfd/syscon-i2c.h
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 0a59249198d34..63ae78b92b086 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1300,6 +1300,13 @@ config MFD_SYSCON
> Select this option to enable accessing system control registers
> via regmap.
>
> +config MFD_SYSCON_I2C
> + bool "System Controller Register R/W Based on I2C Regmap"
> + select REGMAP_I2C
> + help
> + Select this option to enable accessing system control registers
> + via I2C using regmap.
> +
> config MFD_DAVINCI_VOICECODEC
> tristate
> select MFD_CORE
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index f935d10cbf0fc..0aec1f42ac979 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -219,6 +219,7 @@ obj-$(CONFIG_MFD_RK808) += rk808.o
> obj-$(CONFIG_MFD_RN5T618) += rn5t618.o
> obj-$(CONFIG_MFD_SEC_CORE) += sec-core.o sec-irq.o
> obj-$(CONFIG_MFD_SYSCON) += syscon.o
> +obj-$(CONFIG_MFD_SYSCON_I2C) += syscon-i2c.o
> obj-$(CONFIG_MFD_LM3533) += lm3533-core.o lm3533-ctrlbank.o
> obj-$(CONFIG_MFD_VEXPRESS_SYSREG) += vexpress-sysreg.o
> obj-$(CONFIG_MFD_RETU) += retu-mfd.o
> diff --git a/drivers/mfd/syscon-i2c.c b/drivers/mfd/syscon-i2c.c
> new file mode 100644
> index 0000000000000..404e595d7646c
> --- /dev/null
> +++ b/drivers/mfd/syscon-i2c.c
> @@ -0,0 +1,89 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * System Control Driver accessed over I2C
> + *
> + * Copyright (C) 2020 Linaro Ltd.
> + *
> + * Author: Lee Jones <lee.jones@...aro.org>
> + */
> +
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/list.h>
> +#include <linux/mfd/syscon-i2c.h>
> +#include <linux/regmap.h>
> +
> +static DEFINE_SPINLOCK(syscon_i2c_list_slock);
> +static LIST_HEAD(syscon_i2c_list);
> +
> +struct syscon {
> + struct device_node *np;
Note to self: struct i2c_client *client;
> + struct regmap *regmap;
> + struct list_head list;
> +};
> +
> +static const struct regmap_config syscon_i2c_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> +};
> +
> +static struct syscon *of_syscon_i2c_register(struct i2c_client *client)
> +{
> + struct regmap_config syscon_config = syscon_i2c_regmap_config;
> + struct device_node *np = client->dev.of_node;
> + struct syscon *syscon;
> + struct regmap *regmap;
> + int ret;
> +
> + syscon = devm_kzalloc(&client->dev, sizeof(*syscon), GFP_KERNEL);
> + if (!syscon)
> + return ERR_PTR(-ENOMEM);
> +
> + syscon_config.name = of_node_full_name(np);
Note to self: Use dev_name();
> + regmap = devm_regmap_init_i2c(client, &syscon_config);
> + if (IS_ERR(regmap)) {
> + dev_err(&client->dev, "Failed to initialise Regmap I2C\n");
> + ret = PTR_ERR(regmap);
> + return ERR_PTR(ret);
> + }
> +
> + syscon->regmap = regmap;
> + syscon->np = np;
> +
> + spin_lock(&syscon_i2c_list_slock);
> + list_add_tail(&syscon->list, &syscon_i2c_list);
> + spin_unlock(&syscon_i2c_list_slock);
> +
> + return syscon;
> +}
> +
> +static struct regmap *i2c_device_node_get_regmap(struct i2c_client *client)
Note to self: i2c_client_get_regmap()
> +{
> + struct device_node *np = client->dev.of_node;
> + struct syscon *entry, *syscon = NULL;
> +
> + spin_lock(&syscon_i2c_list_slock);
> +
> + list_for_each_entry(entry, &syscon_i2c_list, list)
> + if (entry->np == np) {
> + syscon = entry;
> + break;
> + }
> +
> + spin_unlock(&syscon_i2c_list_slock);
> +
> + if (!syscon)
> + syscon = of_syscon_i2c_register(client);
> +
> + if (IS_ERR(syscon))
> + return ERR_CAST(syscon);
> +
> + return syscon->regmap;
> +}
> +
> +struct regmap *i2c_device_node_to_regmap(struct i2c_client *client)
Note to self: i2c_client_to_regmap()
> +{
> + return i2c_device_node_get_regmap(client);
> +}
> +EXPORT_SYMBOL_GPL(i2c_device_node_to_regmap);
> diff --git a/include/linux/mfd/syscon-i2c.h b/include/linux/mfd/syscon-i2c.h
> new file mode 100644
> index 0000000000000..854e316fec93e
> --- /dev/null
> +++ b/include/linux/mfd/syscon-i2c.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * System Control Driver accessed via I2C
> + *
> + * Copyright (C) 2020 Linaro Ltd.
> + *
> + * Author: Lee Jones <lee.jones@...aro.org>
> + */
> +
> +#ifndef __LINUX_MFD_SYSCON_I2C_H__
> +#define __LINUX_MFD_SYSCON_I2C_H__
> +
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/i2c.h>
> +
> +#ifdef CONFIG_MFD_SYSCON_I2C
> +extern struct regmap *i2c_device_node_to_regmap(struct i2c_client *client);
> +#else
> +static inline struct regmap *i2c_device_node_to_regmap(struct i2c_client *client)
> +{
> + return ERR_PTR(-ENOTSUPP);
> +}
> +#endif
> +
> +#endif /* __LINUX_MFD_SYSCON_I2C_H__ */
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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