i2c: imx: Implement errata ERR007805 or e7805 bus frequency limit

i2c: imx: Implement errata ERR007805 or e7805 bus frequency limit

The i.MX8MP Mask Set Errata for Mask 1P33A, Rev. 2.0 has description of
errata ERR007805 as below. This errata is found on all MX8M{M,N,P,Q},
MX7{S,D}, MX6{UL{,L,Z},S{,LL,X},S,D,DL,Q,DP,QP} . MX7ULP, MX8Q, MX8X
are not affected. MX53 and older status is unknown, as the errata
first appears in MX6 errata sheets from 2016 and the latest errata
sheet for MX53 is from 2015. Older SoC errata sheets predate the
MX53 errata sheet. MX8ULP and MX9 status is unknown as the errata
sheet is not available yet.

"
ERR007805 I2C: When the I2C clock speed is configured for 400 kHz,
the SCL low period violates the I2C spec of 1.3 uS min

Description: When the I2C module is programmed to operate at the
maximum clock speed of 400 kHz (as defined by the I2C spec), the SCL
clock low period violates the I2C spec of 1.3 uS min. The user must
reduce the clock speed to obtain the SCL low time to meet the 1.3us
I2C minimum required. This behavior means the SoC is not compliant
to the I2C spec at 400kHz.

Workaround: To meet the clock low period requirement in fast speed
mode, SCL must be configured to 384KHz or less.
"

Implement the workaround by matching on the affected SoC specific
compatible strings and by limiting the maximum bus frequency in case
the SoC is affected.

Signed-off-by: Marek Vasut <marex@denx.de>
To: linux-i2c@vger.kernel.org
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>