On 07/14/2014 05:03 PM, Lee Jones wrote:
> On Mon, 14 Jul 2014, Stanimir Varbanov wrote:
>> On 07/11/2014 12:07 PM, Lee Jones wrote:
>>> On Thu, 10 Jul 2014, Stanimir Varbanov wrote:
>>>>>>>> The Qualcomm QPNP PMIC chips are components used with the
>>>>>>>> Snapdragon 800 series SoC family. This driver exists
>>>>>>>> largely as a glue mfd component, it exists to be an owner
>>>>>>>> of an SPMI regmap for children devices described in
>>>>>>>> device tree.
>>>>>>>>
>>>>>>>> Signed-off-by: Josh Cartwright <joshc@xxxxxxxxxxxxxx>
>>>>>>>> Signed-off-by: Stanimir Varbanov <svarbanov@xxxxxxxxxx>
>>>>>>>> ---
>>>>>>>> drivers/mfd/Kconfig | 15 ++++++
>>>>>>>> drivers/mfd/Makefile | 1 +
>>>>>>>> drivers/mfd/qpnp-spmi.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++
>>>>>>>> 3 files changed, 145 insertions(+), 0 deletions(-)
>>>>>>>> create mode 100644 drivers/mfd/qpnp-spmi.c
>>>>>>>>
>>>>>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>>>>>>>> index ee8204c..258b733 100644
>>>>>>>> --- a/drivers/mfd/Kconfig
>>>>>>>> +++ b/drivers/mfd/Kconfig
>>>>>>>> @@ -524,6 +524,21 @@ config MFD_PM8921_CORE
>>>>>>>> Say M here if you want to include support for PM8921 chip as a module.
>>>>>>>> This will build a module called "pm8921-core".
>>>>>>>>
>>>>>>>> +config MFD_QPNP_SPMI
>>>>>>>> + tristate "Qualcomm QPNP SPMI PMIC"
>>>>>>>> + depends on ARCH_QCOM || COMPILE_TEST
>>>>>>>> + depends on OF
>>>>>>>> + select MFD_CORE
>>>>>>>> + select REGMAP_SPMI
>>>>>>>> + help
>>>>>>>> + This enables support for the Qualcomm QPNP SPMI PMICs.
>>>>>>>> + These PMICs are currently used with the Snapdragon 800 series of
>>>>>>>> + SoCs. Note, that this will only be useful paired with descriptions
>>>>>>>> + of the independent functions as children nodes in the device tree.
>>>>>>>
>>>>
>>>> <snip>
>>>>
>>>>>>>
>>>>>>>> + * 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.
>>>>>>>> + */
>>>>>>>> +#include <linux/kernel.h>
>>>>>>>> +#include <linux/module.h>
>>>>>>>> +#include <linux/spmi.h>
>>>>>>>> +#include <linux/regmap.h>
>>>>>>>> +#include <linux/of_address.h>
>>>>>>>> +#include <linux/slab.h>
>>>>>>>> +#include <linux/mfd/core.h>
>>>>>>>> +
>>>>>>>> +#define QPNP_RESOURCE_SIZE 256
>>>>>>>> +
>>>>>>>> +static const struct regmap_config qpnp_regmap_config = {
>>>>>>>> + .reg_bits = 16,
>>>>>>>> + .val_bits = 8,
>>>>>>>> + .max_register = 0xffff,
>>>>>>>> +};
>>>>>>>> +
>>>>>>>> +static int qpnp_index_to_resource(struct device_node *np, int index,
>>>>>>>> + struct resource *res)
>>>>>>>> +{
>>>>>>>> + const char *name = NULL;
>>>>>>>> + const __be32 *addrp;
>>>>>>>> + u64 addr;
>>>>>>>> +
>>>>>>>> + addrp = of_get_address(np, index, NULL, NULL);
>>>>>>>> + if (!addrp)
>>>>>>>> + return -EINVAL;
>>>>>>>> +
>>>>>>>> + addr = of_read_number(addrp, 1);
>>>>>>>> + if (addr == OF_BAD_ADDR)
>>>>>>>> + return -EINVAL;
>>>>>>>> +
>>>>>>>> + of_property_read_string_index(np, "reg-names", index, &name);
>>>>>>>> +
>>>>>>>> + res->start = addr;
>>>>>>>> + res->end = addr + QPNP_RESOURCE_SIZE - 1;
>>>>>>>> + res->flags = IORESOURCE_REG;
>>>>>>>> + res->name = name ? name : np->name;
>>>>>>>> +
>>>>>>>> + return 0;
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +static int qpnp_add_device(struct spmi_device *root, struct device_node *child)
>>>>>>>> +{
>>>>>>>> + struct mfd_cell cell = {};
>>>>>>>> + struct resource *res, *r;
>>>>>>>> + int num_resources = 0;
>>>>>>>> + const char *compat;
>>>>>>>> + int ret, i;
>>>>>>>> +
>>>>>>>> + compat = of_get_property(child, "compatible", NULL);
>>>>>>>> + if (!compat)
>>>>>>>> + return -ENODEV;
>>>>>>>> +
>>>>>>>> + while (of_get_address(child, num_resources, NULL, NULL))
>>>>>>>> + num_resources++;
>>>>>>>> +
>>>>>>>> + if (!num_resources)
>>>>>>>> + return -ENODEV;
>>>>>>>> +
>>>>>>>> + res = kcalloc(num_resources, sizeof(*res), GFP_KERNEL);
>>>>>>>> + if (!res)
>>>>>>>> + return -ENOMEM;
>>>>>>>> +
>>>>>>>> + r = res;
>>>>>>>> + for (i = 0; i < num_resources; i++, r++)
>>>>>>>> + qpnp_index_to_resource(child, i, r);
>>>>>>>> +
>>>>>>>> + cell.name = kasprintf(GFP_KERNEL, "%x.%04x.%s", root->usid,
>>>>>>>> + (u16)res[0].start, child->name);
>>>>>>>> + cell.of_compatible = compat;
>>>>>>>> + cell.num_resources = num_resources;
>>>>>>>> + cell.resources = res;
>>>>>>>> +
>>>>>>>> + ret = mfd_add_devices(&root->dev, PLATFORM_DEVID_NONE, &cell, 1,
>>>>>>>> + NULL, 0, NULL);
>>>>>>>> +
>>>>>>>> + kfree(res);
>>>>>>>> + kfree(cell.name);
>>>>>>>> +
>>>>>>>> + return ret;
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +static int qpnp_probe(struct spmi_device *sdev)
>>>>>>>> +{
>>>>>>>> + struct device_node *root = sdev->dev.of_node;
>>>>>>>> + struct device_node *child;
>>>>>>>> + struct regmap *regmap;
>>>>>>>> +
>>>>>>>> + regmap = devm_regmap_init_spmi_ext(sdev, &qpnp_regmap_config);
>>>>>>>> + if (IS_ERR(regmap))
>>>>>>>> + return PTR_ERR(regmap);
>>>>>>>> +
>>>>>>>> + for_each_available_child_of_node(root, child)
>>>>>>>> + qpnp_add_device(sdev, child);
>>>>>>>
>>>>>>> This entire driver looks like a re-write of of_platform_populate().
>>>>>>>
>>>>>>> Why?
>>>>>>
>>>>>> of_platform_populate is not used because the PMIC function resources are
>>>>>> non-translatable. You can see that the resources are of type
>>>>>> IORESOURCE_REG (qpnp_index_to_resource()) not IORESOURCE_MEM or _IO.
>>>>>>
>>>>>> The whole point of this mfd driver is to parse devicetree to prepare
>>>>>> resources for every child and create platform device for it through
>>>>>> mfd_add_devices(). Then the PMIC function driver got its resources and
>>>>>> use them as register addresses passed to regmap. These register accesses
>>>>>> hits the SPMI controller which is the physical interface between PMIC's
>>>>>> and SoC.
>>>>>
>>>>> I can't help but think that if this is required, it should be part of
>>>>> the core OF code, rather than doing your own thing which looks
>>>>> frighteningly like existing framework functionality.
>>>>
>>>> does it make sense to have a common of_mfd code for devicetree parsing?
>>>> Is that discussed already? I mean presently the mfd_cell resources and
>>>> number of resources are passed by the mfd_add_devices users. Is it
>>>> possible to have common code which parses devicetree sub-nodes of the
>>>> parent device_node and fill resources/create platform devices for them.
>>>
>>> I'm not sure it does. Normally users _either_ represent devices in
>>> MFD cells from within the driver _or_ populate using existing DT
>>> interfaces i.e. of_platform_populate(). This is the first time I've
>>> seen someone attempt to parse the entire MFD node structure from
>>> within a driver.
>>
>> Our goal is to use common mfd driver for various Qualcomm PMIC from the
>> same PMIC generation (codenamed QPNP). Presently we have good
>> abstraction of the register manipulation functions through regmap-spmi
>> layer. Using the devicetree to represent different peripherals base
>> addresses (reg property) gives us a benefit by avoiding huge header
>> files in linux/mfd and make flexible transition to new PMIC's which just
>> change the base addresses but keep the IP block the same. This way we
>> should change the devicetree binding without touch the drivers.
>
> I'm still not convinced that you need to write your own parser. If
> you're concerned about not translating the reg property, use (or
> don't) the 'ranges' property accordingly.
Unfortunately "ranges" property doesn't help here. The pmic addresses
parsed from "reg" properties are SPMI addresses (similar to I2C addresses).
--
regards,
Stan
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