dt-bindings: nvmem: Add STM32 factory-programmed romem

Add documentation for STMicroelectronics STM32 Factory-programmed
read only memory area.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/devicetree/bindings/nvmem/st,stm32-romem.txt b/Documentation/devicetree/bindings/nvmem/st,stm32-romem.txt
new file mode 100644 (file)
index 0000000..142a51d
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/st,stm32-romem.txt
@@ -0,0 +1,31 @@
+STMicroelectronics STM32 Factory-programmed data device tree bindings
+
+This represents STM32 Factory-programmed read only non-volatile area: locked
+flash, OTP, read-only HW regs... This contains various information such as:
+analog calibration data for temperature sensor (e.g. TS_CAL1, TS_CAL2),
+internal vref (VREFIN_CAL), unique device ID...
+
+Required properties:
+- compatible:          Should be one of:
+                       "st,stm32f4-otp"
+                       "st,stm32mp15-bsec"
+- reg:                 Offset and length of factory-programmed area.
+- #address-cells:      Should be '<1>'.
+- #size-cells:         Should be '<1>'.
+
+Optional Data cells:
+- Must be child nodes as described in nvmem.txt.
+
+Example on stm32f4:
+       romem: nvmem@1fff7800 {
+               compatible = "st,stm32f4-otp";
+               reg = <0x1fff7800 0x400>;
+               #address-cells = <1>;
+               #size-cells = <1>;
+
+               /* Data cells: ts_cal1 at 0x1fff7a2c */
+               ts_cal1: calib@22c {
+                       reg = <0x22c 0x2>;
+               };
+               ...
+       };