AW: [PATCH 1/1] mfd: da9063: Support SMBus and I2C mode
From: Jonas Mark (BT-FIR/ENG1-Grb) <hidden>
Date: 2021-01-28 16:11:31
Also in:
linux-i2c, lkml
Hi Adam,
quoted
From: Hubert Streidl <redacted> By default the PMIC DA9063 2-wire interface is SMBus compliant. This means the PMIC will automatically reset the interface when the clock signal ceases for more than the SMBus timeout of 35 ms. If the I2C driver / device is not capable of creating atomic I2C transactions, a context change can cause a ceasing of the the clock signal. This can happen if for example a real-time thread is scheduled. Then the DA9063 in SMBus mode will reset the 2-wire interface. Subsequently a write message could end up in the wrong register. This could cause unpredictable system behavior. The DA9063 PMIC also supports an I2C compliant mode for the 2-wire interface. This mode does not reset the interface when the clock signal ceases. Thus the problem depicted above does not occur. This patch makes the I2C mode configurable by device tree. The SMBus compliant mode is kept as the default.Could we not just check the bus' functionality flags and set this accordingly? Something like this is already done in regmap-i2c to determine how to access the device: https://elixir.bootlin.com/linux/latest/source/drivers/base/regmap/regmap-i2c.c#L309 This seems cleaner than a new DT property, or will this not work in this situation?
Thank you for the proposal. We were not aware of this possibility. We experienced the SMBus timeout problem on a i.MX6 Solo. When looking at the i2c-imx driver we see that it defines a list of functionality. return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_READ_BLOCK_DATA; https://elixir.bootlin.com/linux/latest/source/drivers/i2c/busses/i2c-imx.c#L1133 None of that seems to model the inability to perform atomic transactions within the SMBus timeout. This is either a bug of this specific driver or maybe the expressiveness of I2C_FUNC_* is not sufficient. https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/i2c.h#L88 What flag do you think we could check to find out whether the bus is able to obey the SMBus timeout or not?
quoted hunk ↗ jump to hunk
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Signed-off-by: Hubert Streidl <redacted> Signed-off-by: Mark Jonas <redacted> --- Documentation/devicetree/bindings/mfd/da9063.txt | 7 +++++++ drivers/mfd/da9063-core.c | 9 +++++++++ drivers/mfd/da9063-i2c.c | 13 +++++++++++++ include/linux/mfd/da9063/core.h | 1 + include/linux/mfd/da9063/registers.h | 3 +++ 5 files changed, 33 insertions(+)diff --git a/Documentation/devicetree/bindings/mfd/da9063.txtb/Documentation/devicetree/bindings/mfd/da9063.txt index 8da879935c59..256f2a25fe0a 100644--- a/Documentation/devicetree/bindings/mfd/da9063.txt +++ b/Documentation/devicetree/bindings/mfd/da9063.txt@@ -19,6 +19,12 @@ Required properties: - interrupts : IRQ line information. - interrupt-controller +Optional properties: + +- i2c-mode : Switch serial 2-wire interface into I2C mode. Without +this + property the PMIC uses the SMBus mode (resets the interface if the +clock + ceases for a longer time than the SMBus timeout). + Sub-nodes: - regulators : This node defines the settings for the LDOs and BUCKs.@@ -77,6 +83,7 @@ Example: interrupt-parent = <&gpio6>; interrupts = <11 IRQ_TYPE_LEVEL_LOW>; interrupt-controller; + i2c-mode; rtc { compatible = "dlg,da9063-rtc";diff --git a/drivers/mfd/da9063-core.c b/drivers/mfd/da9063-core.c index df407c3afce3..baa1e4310c8c 100644 --- a/drivers/mfd/da9063-core.c +++ b/drivers/mfd/da9063-core.c@@ -162,6 +162,15 @@ int da9063_device_init(struct da9063 *da9063,unsigned int irq) { int ret; + if (da9063->i2cmode) { + ret = regmap_update_bits(da9063->regmap, DA9063_REG_CONFIG_J, + DA9063_TWOWIRE_TO, 0); + if (ret < 0) { + dev_err(da9063->dev, "Cannot enable I2C mode.\n"); + return -EIO; + } + } + ret = da9063_clear_fault_log(da9063); if (ret < 0) dev_err(da9063->dev, "Cannot clear fault log\n"); diff --git a/drivers/mfd/da9063-i2c.c b/drivers/mfd/da9063-i2c.c index 3781d0bb7786..af0bf13ab43e 100644--- a/drivers/mfd/da9063-i2c.c +++ b/drivers/mfd/da9063-i2c.c@@ -351,6 +351,17 @@ static const struct of_device_id da9063_dt_ids[] = { { } }; MODULE_DEVICE_TABLE(of, da9063_dt_ids); + +static void da9063_i2c_parse_dt(struct i2c_client *client, struct +da9063 *da9063) { + struct device_node *np = client->dev.of_node; + + if (of_property_read_bool(np, "i2c-mode")) + da9063->i2cmode = true; + else + da9063->i2cmode = false; +} + static int da9063_i2c_probe(struct i2c_client *i2c, const struct i2c_device_id *id) { @@ -366,6 +377,8@@ staticquoted
int da9063_i2c_probe(struct i2c_client *i2c, da9063->chip_irq = i2c->irq; da9063->type = id->driver_data; + da9063_i2c_parse_dt(i2c, da9063); + ret = da9063_get_device_type(i2c, da9063); if (ret) return ret;diff --git a/include/linux/mfd/da9063/core.hb/include/linux/mfd/da9063/core.h index fa7a43f02f27..866864c50f78 100644--- a/include/linux/mfd/da9063/core.h +++ b/include/linux/mfd/da9063/core.h@@ -77,6 +77,7 @@ struct da9063 { enum da9063_type type; unsigned char variant_code; unsigned int flags; + bool i2cmode; /* Control interface */ struct regmap *regmap;diff --git a/include/linux/mfd/da9063/registers.hb/include/linux/mfd/da9063/registers.h index 1dbabf1b3cb8..6e0f66a2e727 100644--- a/include/linux/mfd/da9063/registers.h +++ b/include/linux/mfd/da9063/registers.h@@ -1037,6 +1037,9 @@ #define DA9063_NONKEY_PIN_AUTODOWN 0x02 #define DA9063_NONKEY_PIN_AUTOFLPRT 0x03 +/* DA9063_REG_CONFIG_J (addr=0x10F) */ +#define DA9063_TWOWIRE_TO 0x40 + /* DA9063_REG_MON_REG_5 (addr=0x116) */ #define DA9063_MON_A8_IDX_MASK 0x07 #define DA9063_MON_A8_IDX_NONE 0x00 --2.25.1
Cheers, Mark