Signed-off-by: Przemyslaw Marczak p.marczak@samsung.com --- doc/driver-model/dm-pmic-framework.txt | 450 +++++++++++++++++++++++++++++++++ 1 file changed, 450 insertions(+) create mode 100644 doc/driver-model/dm-pmic-framework.txt
diff --git a/doc/driver-model/dm-pmic-framework.txt b/doc/driver-model/dm-pmic-framework.txt new file mode 100644 index 0000000..1b69eee --- /dev/null +++ b/doc/driver-model/dm-pmic-framework.txt @@ -0,0 +1,450 @@ +# +# (C) Copyright 2014 Samsung Electronics +# Przemyslaw Marczak p.marczak@samsung.com +# +# SPDX-License-Identifier: GPL-2.0+ +# + +PMIC framework based on Driver Model +==================================== +TOC: +1. Introduction +2. How does it work +3. Driver API +4. Simple UCLASS_PMIC driver +5. Pmic command +6. Uclass UCLASS_PMIC_REGULATOR API +7. Simple UCLASS_PMIC_REGULATOR driver +8. Regulator command + +1. Introduction +=============== +This is an introduction to driver-model multi class PMIC support. +It starts with UCLASS_PMIC - a common PMIC class type for I/O, which +doesn't need to implement any specific operations and features beside +the platform data, which is a 'struct pmic_platdata' defined in file: +- 'include/power/pmic.h' + +New files: +- pmic-uclass.c - provides a common code for UCLASS_PMIC drivers +- pmic_i2c.c - provides dm interface for i2c pmic drivers +- pmic_spi.c - provides dm interface for spi pmic drivers + +Those files are based on a current PMIC framework files and code. +And the new files are introduced to avoid code mess and allow to +make an easy drivers migration. The old pmic is still kept. + +Changes: +- add uclass-id: UCLASS_PMIC +- add new configs: + CONFIG_DM_PMIC - enables driver model pmic framework and requires one + or both of: + CONFIG_DM_PMIC_SPI - enables an interface to pmic SPI + CONFIG_DM_PMIC_I2C - enables an interface to pmic I2C + +The old pmic interface API worked very well so it is kept, but the framework +architecture is changed. + +2. How doees it work +==================== +The framework init starts in file: drivers/power/pmic-uclass.c +The function pmic_init_dm() looks after the 'pmic' alias in the device-tree +and do the driver bind. +If board uses more than one PMIC device, then a few 'pmic' aliases should +be defined with numbers, e.g. pmic0, pmic1... + +Note: +The I2C doesn't use the driver model yet, so the drivers are bind thanks to the +'pmic' alias. + +3. PMIC drivers API +=================== +The new API is as simple as previously: + +File: drivers/power/pmic-uclass.c: +- void power_init_dm(void) + The main init function, called after the i2c init and before power_init_board. + Bind the UCLASS_PMIC drivers. + +- struct udevice *pmic_get_by_name(int uclass_id, char *name) + This function provides similar function as old pmic_get(), but the returned + device pointer doesn't require any allocation. + The uclass_id argument if to chose proper device uclass, e.g. pmic or next + others, pmic related. + +- struct udevice *pmic_get_by_interface(int uclass_id, int bus, int addr_cs) + This is similar function as previous but is designed for boards with more + than one pmic device or the same device instances. In this case we can't + get the device by the name, so the best and accurate method is to get it by + known uclass, bus and address or cs(spi). This is new framework feature. + +- const char *pmic_if_str(int interface) + This function returns the interface name string for i2c or spi, and uses + pmic interface enum from: include/power/pmic.h + +- int pmic_check_reg(struct pmic_platdata *p, unsigned reg) + This function check if the given register number is valid for the given + pmic_platdata. + +- int pmic_reg_write(struct udevice *dev, unsigned reg, unsigned val) + The same functionality as in old framework but changed to driver-model. + +- int pmic_reg_read(struct udevice *dev, unsigned reg, unsigned *val) + The same functionality as in old framework but changed to driver-model. + +- int pmic_probe(struct udevice *dev, struct spi_slave *spi_slave) + The same functionality as in an old framework but changed to driver model, + and extended by support to both pmic interfaces. + +The below functions, are implemented with use of common calls, described above. + +File: drivers/power/pmic_i2c.c: +- int pmic_i2c_reg_write(struct udevice *dev, unsigned reg, unsigned val) +- int pmic_i2c_reg_read(struct udevice *dev, unsigned reg, unsigned *val) +- int pmic_i2c_probe(struct udevice *dev) + +File: drivers/power/pmic_spi.c: +- int pmic_spi_reg_write(struct udevice *dev, unsigned reg, unsigned val) +- int pmic_spi_reg_read(struct udevice *dev, unsigned reg, unsigned *val) +- struct spi_slave *pmic_spi_probe(struct udevice *dev) + +4. Simple UCLASS_PMIC driver +============================ +At this stage the framework supports only drivers that have proper fdt alias. +The alias is "pmic" or "pmicN". + +The exaple of dts node(): + aliases { + ... + ... + pmic0 = &simple_pmic0; + } + + i2c@some_addr { + ; some i2c data + + simple_pmic0: simple_pmic@09 { + compatible = "vandor, simple_pmic"; + reg = <0x09 0 0>; + } + +The exaple of driver code: + +/** + * simple_pmic_probe(...) - this function is optional and is a preffered way + * to bind the "simple regulator" device. + * Than we have: + * device: "simple_pmic" - provides device I/O + * device: "simple regulator" - provides regualtor operations and is binded + * as a child of "simple_pmic" + */ +static int simple_pmic_probe(struct udevice *parent) +{ + struct udevice *reg_dev; + struct driver *reg_drv; + int ret; + + reg_drv = lists_driver_lookup_name("simple regulator"); + if (!reg_drv) { + error("%s regulator driver not found!\n", parent->name); + return 0; + } + + if (!parent->platdata) { + error("%s platdata not found!\n", parent->name); + return -EINVAL; + } + + ret = device_bind(parent, reg_drv, parent->name, parent->platdata, + parent->of_offset, ®_dev); + if (ret) + error("%s regulator bind failed", parent->name); + + /** + * Return an error only if no parent platdata set + * so if no regulator found - still have pmic I/O. + * This scheme will be used in most board configs. + */ + return 0; +} + +static int simple_pmic_ofdata_to_platdata(struct udevice *dev) +{ + struct pmic_platdata *pl = dev->platdata; + + /** + * Here, driver should init the platdata structure based on device-tree, + * The fields bus, interface, byte_order and the struct spi or i2c, + * provide information about I/O acces, so are required. + */ + const void *blob = gd->fdt_blob; + int node = dev->of_offset; + int parent; + + pl->interface = PMIC_I2C; + pl->regs_num = PMIC_NUM_OF_REGS; + + parent = fdt_parent_offset(blob, node); + + if (parent < 0) { + error("%s: Cannot find node parent", __func__); + return -EINVAL; + } + + pl->bus = i2c_get_bus_num_fdt(parent); + if (pl->bus < 0) { + debug("%s: Cannot find bus num\n", __func__); + return -EINVAL; + } + + pl->hw.i2c.addr = fdtdec_get_int(blob, node, "reg", SIMPLE_PMIC_I2C_ADDR); + pl->hw.i2c.tx_num = 1; + + return 0; +} + +static const struct udevice_id simple_pmic_ids[] = { + { .compatible = "vendor,simple_pmic"}, + { } +}; + +U_BOOT_DRIVER(simple_pmic) = { + .name = "simple pmic", + .id = UCLASS_PMIC, + .of_match = simple_pmic_ids, + .probe = simple_pmic_probe, + .ofdata_to_platdata = simple_pmic_ofdata_to_platdata, + .platdata_auto_alloc_size = sizeof(struct pmic_platdata), +}; + +5. Pmic command +=============== +This is based on an old pmic command code - the new one uses +the driver model pmic API. The previous pmic I/O functionalities, +stays unchanged. And now read/write is the main pmic command +purpose. This command can use only UCLASS_PMIC devices, +since this uclass is designed for pmic I/O operations only. + +Command options (pmic [option]): +- list - list available PMICs +- dev <id> - set id to current pmic device +- pmic dump - dump registers +- pmic read <reg> - read register +- pmic write <reg> <value> - write register + +Example of usage: +# pmic list - chose one dev Id, e.g. 3 +# pmic dev 3 - set dev 3 as current device +# pmic dump - dump the registers of pmic dev id 3 +# pmic read 0x0 - read the register of addres 0x0 +# pmic write 0x0 0x1 - write 0x1 to the register of addres 0x0 + +The user interface is similar to the 'mmc' command. + +Each pmic device driver should provide at least UCLASS_PMIC support, +as a basic pmic device I/O interface. + +6. Uclass UCLASS_PMIC_REGULATOR API +=================================== +To use the regulator API, config: CONFIG_DM_REGULATOR is required. + +Driver API is simple and clear: +To get the regulator device we can use two functions: +- pmic_get_by_name(...) +- pmic_get_by_interface(...) + +This returns "struct udevice *" pointer to uclass regulator device, +which can provide API functions. + +To operate on device regulators, we can use API functions +(if provided by the driver): +- pmic_ldo_cnt(...) +- pmic_buck_cnt(...) +- pmic_get_ldo_val(...) +- pmic_set_ldo_val(...) +- pmic_get_ldo_mode(...) +- pmic_set_ldo_mode(...) +- pmic_get_buck_val(...) +- pmic_set_buck_val(...) +- pmic_get_buck_mode(...) +- pmic_set_buck_mode(...) + +For detailed description please look into the file: +- include/power/regulator.h + +7. Simple UCLASS_PMIC_REGULATOR driver +====================================== +The regulator ops implementation can be different for each driver, +so this is only a piece of driver design. +As a reference, please take the MAX77686 pmic and regulator drivers. +- drivers/power/pmic/max77686.c +- drivers/power/regulator/max77686.c + +The regulator driver code should look like below: +(Please read the 'include/power/regulator.h' for more details) + +Note: +The regulator device should act as a child of pmic device. +This is a natural scheme of a physical PMIC IC: + +Some PMIC physical IC: + |_ dev pmic (parent) - simple and sufficient for the most board configs + |_ dev regulator (child) - provide regulator operations + |_ dev other (child) - some other pmic uclasses, (in the future) + +struct regulator_desc *simple_regulator_get_val_desc(struct udevice *dev, + int d_type, int d_num) +{ + /* Here returns regulator value descriptor */ + return NULL; +} + +static struct regulator_mode_desc * +simple_regulator_get_mode_desc_array(struct udevice *dev, int d_type, int d_num, + int *d_mode_cnt) +{ + /* Here return arra of mode descriptors for given device */ + return NULL; +} + +static int simple_regulator_get_ldo_cnt(struct udevice *dev) +{ + /* Here return regulators ldo count */ + return 0; +} + +static int simple_regulator_get_buck_cnt(struct udevice *dev) +{ + /* Here return regulator buck count */ + return 0; +} + +static int simple_regulator_ldo_val(struct udevice *dev, int op, + int ldo, int *uV) +{ + /* Here return or sets given ldo value in uV */ + return 0; +} + +static int simple_regulator_buck_val(struct udevice *dev, int op, + int buck, int *uV) +{ + /* Here return or sets given buck value in uV */ + return 0; +} + +static int simple_regulator_ldo_mode(struct udevice *dev, int op, int ldo, + int *opmode) +{ + /* Here return or sets regulator ldo mode */ + return 0; +} + +static int simple_regulator_buck_mode(struct udevice *dev, int op, int buck, + int *opmode) +{ + /* Here return or sets regulator buck mode */ + return 0; +} + +static int simple_regulator_ofdata_to_platdata(struct udevice *dev) +{ + /** + * PMIC Interface, Case 1: common + * If PMIC uses only one (SPI/I2C) physical interface for driving + * it's functionalities. + * + * Then the bind of "simple regulator" device in the "simple pmic" probe + * is called with args: + * ret = device_bind(parent, reg_drv, parent->name, parent->platdata, + * parent->of_offset, ®_dev); + */ + + /** + * PMIC Interface, case 2: independent + * If PMIC uses more then one (SPI/I2C) physical interfaces for driving + * it's functionalities. + * + * Then the bind of "simple regulator" device in the "simple pmic" + * drivers 'probe', is called with args: + * ret = device_bind(parent, reg_drv, parent->name, NULL, + * regulator_fdt_of_offset, ®_dev); + * + * In this case "driver.platdata_auto_alloc_size" + */ + + /** + * Here driver should get the 'regulator-voltage' node data + * into a proper descriptors. + * Actually there is no standard voltage description in dts, + * but please check trats2 or odroid dts files and regulator/max77686.c + * driver file to check some simple solution. + * + */ + return 0; +} + +static const struct dm_regulator_ops simple_regulator_ops = { + .get_ldo_cnt = simple_regulator_get_ldo_cnt, + .get_buck_cnt = simple_regulator_get_buck_cnt, + .get_val_desc = simple_regulator_get_val_desc, + .get_mode_desc_array = simple_regulator_get_mode_desc_array, + .ldo_val = simple_regulator_ldo_val, + .buck_val = simple_regulator_buck_val, + .ldo_mode = simple_regulator_ldo_mode, + .buck_mode = simple_regulator_buck_mode, +}; + +U_BOOT_DRIVER(simple_regulator) = { + .name = "simple regulator", + .id = UCLASS_PMIC_REGULATOR, + .ops = &simple_regulator_ops, + .ofdata_to_platdata = reg_simple_regulator_ofdata_to_platdata, + .priv_auto_alloc_size = sizeof(struct simple_regulator_info), + + /** + * .platdata_auto_alloc_size - is optional, only if regulator uses + * a different interface than parent pmic. + */ + .platdata_auto_alloc_size = sizeof(struct pmic_platdata), +}; + +8. Regulator command +==================== +The extension for 'pmic' command is a 'regulator' command. +This actually uses the same code, but provides an interface +to pmic optional 'UCLASS_PMIC_REGULATOR' operations. + +If pmic device driver provides support to this another pmic +uclass, then this command provides useful user interface. + +This was designed to allow safe I/O access to pmic device +without the pmic documentation. If driver provide each regulator +- value and mode descriptor - then user can operate on it. + +Command options (regulator [option]): +- list - list UCLASS regulator devices +- dev [id] - show or set current regulator device +- dump - dump registers of current regulator +- [ldo/buck][N] [name/state/desc]- print regulator(s) info +- [ldoN/buckN] [setval/setmode] [mV/modeN] [-f] - set val (mV) +(forcibly) or mode - only if desc available + +Example of usage: +regulator list - look after regulator 'Id' number +regulator dev 'Id' - set current device +regulator ldo state - list state of current device all ldo's +regulator ldo desc - list ldo's descriptors +regulator ldo1 setval 1000 - set device ldo 1 voltage to 1000mV +regulator ldo1 setval 1200 -f - if value exceeds limits - set force +regulator ldo1 setmode 5 - set device ldo 1 mode to '5' (force no available) + +The same for 'buck' regulators. + +Note: +The regulator descriptor 'min' and 'max' limits prevents setting +unsafe value. But sometimes it is useful to change the regulator +value for some test - so the force option (-f) is available. +This option is not available for change the mode, since this depends +on a pmic device design, but the required voltage value can change, +e.g. if some hardware uses pins header.