Date:   Thu, 2 Nov 2017 14:35:50 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Marc CAPDEVILLE <m.capdeville@...log.org>
CC:     Kevin Tsai <ktsai@...ellamicro.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Wolfram Sang <wsa@...-dreams.de>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH v4] iio : Add cm3218 smbus ara and acpi support

On Fri, 27 Oct 2017 18:27:02 +0200
Marc CAPDEVILLE <m.capdeville@...log.org> wrote:

> On asus T100, Capella cm3218 chip is implemented as ambiant light
> sensor. This chip expose an smbus ARA protocol device on standard
> address 0x0c. The chip is not functional before all alerts are
> acknowledged.
> On asus T100, this device is enumerated on ACPI bus and the
> description give tow I2C connection. The first is the connection to
> the ARA device and the second gives the real address of the device.
> 
> So, on device probe,If the i2c address is the ARA address and the
> device is enumerated via acpi, we lookup for the real address in
> the ACPI resource list and change it in the client structure.
> if an interrupt resource is given, and only for cm3218 chip,
> we declare an smbus_alert device.
> 
> Signed-off-by: Marc CAPDEVILLE <m.capdeville@...log.org>

Wolfram - this needs input from you on how to neatly handle
an ACPI registered ARA.

Thanks,

Jonathan
> ---
> v4 :
>    - rework acpi i2c adress lookup due to bad commit being sent.
> 
> v3 :
>    - rework acpi i2c adress lookup
>    - comment style cleanup
>    - add prefix cm32181_to constantes and macros
> 
> v2 :
>    - cm3218 support always build
>    - Cleanup of unneeded #if statement
>    - Beter identifying chip in platform device, acpi and of_device
> 
>  drivers/iio/light/cm32181.c | 202
> ++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 185
> insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/iio/light/cm32181.c b/drivers/iio/light/cm32181.c
> index d6fd0dace74f..f1a7495e851b 100644
> --- a/drivers/iio/light/cm32181.c
> +++ b/drivers/iio/light/cm32181.c
> @@ -18,8 +18,12 @@
>  #include <linux/iio/sysfs.h>
>  #include <linux/iio/events.h>
>  #include <linux/init.h>
> +#include <linux/i2c-smbus.h>
> +#include <linux/acpi.h>
> +#include <linux/of_device.h>
> +#include <linux/resource_ext.h>
>  
> -/* Registers Address */
> +/* Registers Addresses */
>  #define CM32181_REG_ADDR_CMD		0x00
>  #define CM32181_REG_ADDR_ALS		0x04
>  #define CM32181_REG_ADDR_STATUS		0x06
> @@ -45,18 +49,25 @@
>  #define CM32181_MLUX_PER_BIT_BASE_IT	800000	/* Based
> on IT=800ms */ #define	CM32181_CALIBSCALE_DEFAULT	1000
>  #define CM32181_CALIBSCALE_RESOLUTION	1000
> -#define MLUX_PER_LUX			1000
> +#define CM32181_MLUX_PER_LUX			1000
> +
> +#define CM32181_ID			0x81
> +#define CM3218_ID			0x18
> +
> +#define CM3218_ARA_ADDR			0x0c
>  
>  static const u8 cm32181_reg[CM32181_CONF_REG_NUM] = {
>  	CM32181_REG_ADDR_CMD,
>  };
>  
> -static const int als_it_bits[] = {12, 8, 0, 1, 2, 3};
> -static const int als_it_value[] = {25000, 50000, 100000, 200000,
> 400000, +static const int cm32181_als_it_bits[] = {12, 8, 0, 1, 2, 3};
> +static const int cm32181_als_it_value[] = {25000, 50000, 100000,
> 200000, 400000, 800000};
>  
>  struct cm32181_chip {
>  	struct i2c_client *client;
> +	int chip_id;
> +	struct i2c_client *ara;
>  	struct mutex lock;
>  	u16 conf_regs[CM32181_CONF_REG_NUM];
>  	int calibscale;
> @@ -81,7 +92,7 @@ static int cm32181_reg_init(struct cm32181_chip
> *cm32181) return ret;
>  
>  	/* check device ID */
> -	if ((ret & 0xFF) != 0x81)
> +	if ((ret & 0xFF) != cm32181->chip_id)
>  		return -ENODEV;
>  
>  	/* Default Values */
> @@ -103,7 +114,7 @@ static int cm32181_reg_init(struct cm32181_chip
> *cm32181) /**
>   *  cm32181_read_als_it() - Get sensor integration time (ms)
>   *  @cm32181:	pointer of struct cm32181
> - *  @val2:	pointer of int to load the als_it value.
> + *  @val2:	pointer of int to load the cm32181_als_it value.
>   *
>   *  Report the current integartion time by millisecond.
>   *
> @@ -117,9 +128,9 @@ static int cm32181_read_als_it(struct
> cm32181_chip *cm32181, int *val2) als_it =
> cm32181->conf_regs[CM32181_REG_ADDR_CMD]; als_it &=
> CM32181_CMD_ALS_IT_MASK; als_it >>= CM32181_CMD_ALS_IT_SHIFT;
> -	for (i = 0; i < ARRAY_SIZE(als_it_bits); i++) {
> -		if (als_it == als_it_bits[i]) {
> -			*val2 = als_it_value[i];
> +	for (i = 0; i < ARRAY_SIZE(cm32181_als_it_bits); i++) {
> +		if (als_it == cm32181_als_it_bits[i]) {
> +			*val2 = cm32181_als_it_value[i];
>  			return IIO_VAL_INT_PLUS_MICRO;
>  		}
>  	}
> @@ -142,14 +153,14 @@ static int cm32181_write_als_it(struct
> cm32181_chip *cm32181, int val) u16 als_it;
>  	int ret, i, n;
>  
> -	n = ARRAY_SIZE(als_it_value);
> +	n = ARRAY_SIZE(cm32181_als_it_value);
>  	for (i = 0; i < n; i++)
> -		if (val <= als_it_value[i])
> +		if (val <= cm32181_als_it_value[i])
>  			break;
>  	if (i >= n)
>  		i = n - 1;
>  
> -	als_it = als_it_bits[i];
> +	als_it = cm32181_als_it_bits[i];
>  	als_it <<= CM32181_CMD_ALS_IT_SHIFT;
>  
>  	mutex_lock(&cm32181->lock);
> @@ -195,7 +206,7 @@ static int cm32181_get_lux(struct cm32181_chip
> *cm32181) lux *= ret;
>  	lux *= cm32181->calibscale;
>  	lux /= CM32181_CALIBSCALE_RESOLUTION;
> -	lux /= MLUX_PER_LUX;
> +	lux /= CM32181_MLUX_PER_LUX;
>  
>  	if (lux > 0xFFFF)
>  		lux = 0xFFFF;
> @@ -263,9 +274,9 @@ static ssize_t cm32181_get_it_available(struct
> device *dev, {
>  	int i, n, len;
>  
> -	n = ARRAY_SIZE(als_it_value);
> +	n = ARRAY_SIZE(cm32181_als_it_value);
>  	for (i = 0, len = 0; i < n; i++)
> -		len += sprintf(buf + len, "0.%06u ",
> als_it_value[i]);
> +		len += sprintf(buf + len, "0.%06u ",
> cm32181_als_it_value[i]); return len + sprintf(buf + len, "\n");
>  }
>  
> @@ -298,12 +309,89 @@ static const struct iio_info cm32181_info = {
>  	.attrs			= &cm32181_attribute_group,
>  };
>  
> +#if defined(CONFIG_ACPI)
> +/* Filter acpi resources for a real i2c address on same adapter */
> +static int cm3218_filter_i2c_address(struct acpi_resource *ares,
> void *data) +{
> +	struct i2c_client *client = data;
> +	struct acpi_resource_i2c_serialbus *sb;
> +	acpi_status status;
> +	acpi_handle adapter_handle;
> +
> +	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
> +		return 1;
> +
> +	sb = &ares->data.i2c_serial_bus;
> +	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
> +		return 1;
> +
> +	status = acpi_get_handle(ACPI_HANDLE(&client->dev),
> +				 sb->resource_source.string_ptr,
> +				 &adapter_handle);
> +	if (ACPI_FAILURE(status))
> +		return status;
> +
> +	if (adapter_handle != ACPI_HANDLE(&client->adapter->dev))
> +		return 1;
> +
> +	if (sb->slave_address == CM3218_ARA_ADDR)
> +		return 1;
> +
> +	return AE_OK;
> +}
> +
> +/* Get the real i2c address from acpi resources */
> +static int cm3218_acpi_get_address(struct i2c_client *client)
> +{
> +	int ret;
> +	struct acpi_device *adev;
> +	LIST_HEAD(res_list);
> +	struct resource_entry *res_entry;
> +	struct acpi_resource *ares;
> +	struct acpi_resource_i2c_serialbus *sb;
> +
> +	adev = ACPI_COMPANION(&client->dev);
> +	if (!adev)
> +		return -ENODEV;
> +
> +	ret = acpi_dev_get_resources(adev,
> +				     &res_list,
> +				     cm3218_filter_i2c_address,
> +				     client);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* get first resource */
> +	res_entry = list_entry(&res_list, struct resource_entry,
> node);
> +	ares = (struct acpi_resource *)res_entry->res;
> +	sb = &ares->data.i2c_serial_bus;
> +
> +	/* set i2c address */
> +	client->addr = sb->slave_address;
> +	client->flags &= ~I2C_CLIENT_TEN;
> +	if (sb->access_mode == ACPI_I2C_10BIT_MODE)
> +		client->flags |= I2C_CLIENT_TEN;
> +
> +	acpi_dev_free_resource_list(&res_list);
> +
> +	return 0;
> +}
> +#else
> +static inline int cm3218_acpi_get_address(struct i2c_client *client)
> +{
> +	return -ENODEV;
> +}
> +#endif
> +
>  static int cm32181_probe(struct i2c_client *client,
>  			const struct i2c_device_id *id)
>  {
>  	struct cm32181_chip *cm32181;
>  	struct iio_dev *indio_dev;
>  	int ret;
> +	struct i2c_smbus_alert_setup ara_setup;
> +	const struct of_device_id *of_id;
> +	const struct acpi_device_id *acpi_id;
>  
>  	indio_dev = devm_iio_device_alloc(&client->dev,
> sizeof(*cm32181)); if (!indio_dev) {
> @@ -323,11 +411,65 @@ static int cm32181_probe(struct i2c_client
> *client, indio_dev->name = id->name;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  
> +	/* Lookup for chip ID from platform, acpi or of device table
> */
> +	if (id) {
> +		cm32181->chip_id = id->driver_data;
> +	} else if (ACPI_COMPANION(&client->dev)) {
> +		acpi_id =
> acpi_match_device(client->dev.driver->acpi_match_table,
> +					    &client->dev);
> +		if (!acpi_id)
> +			return -ENODEV;
> +
> +		cm32181->chip_id =
> (kernel_ulong_t)acpi_id->driver_data;
> +	} else if (client->dev.of_node) {
> +		of_id =
> of_match_device(clients->dev.driver->of_match_table,
> +					&client->dev);
> +		if (!of_id)
> +			return -ENODEV;
> +
> +		cm32181->chip_id = (kernel_ulong_t)of_id->data;
> +	} else {
> +		return -ENODEV;
> +	}
> +
> +	if (cm32181->chip_id == CM3218_ID) {
> +		if (client->addr == CM3218_ARA_ADDR) {
> +			/*
> +			 * In case first address is the ARA device
> +			 * lookup for a second one in acpi resources
> if
> +			 * this client is enumerated on acpi
> +			 */
> +			ret = cm3218_acpi_get_address(client);
> +			if (ret < 0)
> +				return -ENODEV;

This bares so little resemblance to existing uses of the ARA
infrastructure that I'm not going to take this until Wolfram
has time to look at it.

In all other instances the setup_smbus_alert stuff has been
done from a bus driver, not a client driver.

Unfortunately ACPI support is thin on the ground so it may be
this is the only way we can do it.

There was a relevant patch from Srinivas that google found
for me: https://patchwork.ozlabs.org/patch/386410/

This ensures that we probe the device on the valid address
not the ARA.

Looks like Srinivas' patch never went anywhere.  However
I think it was correct in it's assumption that this sort
of support should be in the core.

> +		}
> +
> +#ifdef CONFIG_I2C_SMBUS
> +		if (client->irq > 0) {
> +			/* setup smb alert device */
> +			ara_setup.irq = client->irq;
> +			ara_setup.alert_edge_triggered = 0;
> +			cm32181->ara =
> i2c_setup_smbus_alert(client->adapter,
> +
> &ara_setup);
> +			if (!cm32181->ara)
> +				return -ENODEV;
> +		} else {
> +			return -ENODEV;
> +		}
> +#else
> +		return -ENODEV;
> +#endif
> +	}
> +
>  	ret = cm32181_reg_init(cm32181);
>  	if (ret) {
>  		dev_err(&client->dev,
>  			"%s: register init failed\n",
>  			__func__);
> +
> +		if (cm32181->ara)
> +			i2c_unregister_device(cm32181->ara);
> +
>  		return ret;
>  	}
>  
> @@ -336,32 +478,58 @@ static int cm32181_probe(struct i2c_client
> *client, dev_err(&client->dev,
>  			"%s: regist device failed\n",
>  			__func__);
> +
> +		if (cm32181->ara)
> +			i2c_unregister_device(cm32181->ara);
> +
>  		return ret;
>  	}
>  
>  	return 0;
>  }
>  
> +static int cm32181_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct cm32181_chip *cm32181 = iio_priv(indio_dev);
> +
> +	if (cm32181->ara)
> +		i2c_unregister_device(cm32181->ara);
> +
> +	return 0;
> +};
> +
>  static const struct i2c_device_id cm32181_id[] = {
> -	{ "cm32181", 0 },
> +	{ "cm32181", CM32181_ID },
> +	{ "cm3218", CM3218_ID },
>  	{ }
>  };
>  
>  MODULE_DEVICE_TABLE(i2c, cm32181_id);
>  
>  static const struct of_device_id cm32181_of_match[] = {
> -	{ .compatible = "capella,cm32181" },
> +	{ .compatible = "capella,cm32181", (void *)CM32181_ID },
> +	{ .compatible = "capella,cm3218",  (void *)CM3218_ID },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(of, cm32181_of_match);
>  
> +static const struct acpi_device_id cm32181_acpi_match[] = {
> +	{ "CPLM3218", CM3218_ID },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, cm32181_acpi_match);
> +
>  static struct i2c_driver cm32181_driver = {
>  	.driver = {
>  		.name	= "cm32181",
>  		.of_match_table = of_match_ptr(cm32181_of_match),
> +		.acpi_match_table = ACPI_PTR(cm32181_acpi_match),
>  	},
>  	.id_table       = cm32181_id,
>  	.probe		= cm32181_probe,
> +	.remove		= cm32181_remove,
>  };
>  
>  module_i2c_driver(cm32181_driver);

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