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SubjectRe: [RFC PATCH v2 1/5] mfd: qpnp: add support for Qualcomm QPNP PMICs
Hi,

+Rob

Rob I used your old email, sorry about that.

<snip>

>>>> 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@codeaurora.org>
>>>> Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com>
>>>> ---
>>>> 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.

Lee,

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.


Rob, Grant I hope you guys have something to say here?


>
> Either way, I'm going to need a DT Ack before I accept this.
>

Sure.

--
regards,
Stan


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