From: methanal <baclo...@tuta.io>

Some replacement displays include third-party touch ICs which do not
expose the function number and the interrupt status in its PDT entries.

OnePlus 6 (original touch IC)
  rmi4_i2c 12-0020: read 6 bytes at 0x00e3: 0 (2b 22 0d 06 01 01)

OnePlus 6 (aftermarket touch IC)
  rmi4_i2c 12-0020: read 6 bytes at 0x00e3: 0 (2c 23 0d 06 00 00)

Introduce a new devicetree property `syna,pdt-desc` which can be used to
provide platform-specific fallback values for users with a replacement
display with an aftermarket touch IC.

Signed-off-by: methanal <baclo...@tuta.io>
[codeflow adjustments, checkpatch fixes, wording]
Signed-off-by: Caleb Connolly <caleb.conno...@linaro.org>
Signed-off-by: David Heidelberg <da...@ixit.cz>
---
 drivers/input/rmi4/rmi_driver.c | 73 ++++++++++++++++++++++++++++++++++++-----
 drivers/input/rmi4/rmi_driver.h |  2 ++
 include/linux/rmi.h             |  3 ++
 3 files changed, 70 insertions(+), 8 deletions(-)

diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
index 
2790f00a58bc66c04656d0cd1b4afe9f843ee093..f233c0b1f8e6a936089fd81344c46b6741d3d82d
 100644
--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -461,9 +461,10 @@ static int rmi_driver_reset_handler(struct rmi_device 
*rmi_dev)
        return 0;
 }
 
-static int rmi_read_pdt_entry(struct rmi_device *rmi_dev,
-                             struct pdt_entry *entry, u16 pdt_address)
+static int rmi_read_pdt_entry(struct rmi_device *rmi_dev, struct pdt_entry 
*entry,
+                             struct pdt_scan_state *state, u16 pdt_address)
 {
+       const struct rmi_device_platform_data *pdata = 
rmi_get_platform_data(rmi_dev);
        u8 buf[RMI_PDT_ENTRY_SIZE];
        int error;
 
@@ -474,6 +475,21 @@ static int rmi_read_pdt_entry(struct rmi_device *rmi_dev,
                return error;
        }
 
+       if (pdata->pdt_fallback_size > state->pdt_count * RMI_OF_PDT_DESC_CELLS 
+ 1) {
+               /* Use the description bytes from DT */
+               buf[5] = pdata->pdt_fallback_desc[state->pdt_count * 
RMI_OF_PDT_DESC_CELLS];
+               buf[4] = pdata->pdt_fallback_desc[state->pdt_count * 
RMI_OF_PDT_DESC_CELLS + 1];
+
+               error = rmi_read_block(rmi_dev, pdt_address, buf,
+                               RMI_PDT_ENTRY_SIZE - 2);
+               if (error) {
+                       dev_err(&rmi_dev->dev,
+                                       "Read PDT entry at %#06x failed, code: 
%d.\n",
+                                       pdt_address, error);
+                       return error;
+               }
+       }
+
        entry->page_start = pdt_address & RMI4_PAGE_MASK;
        entry->query_base_addr = buf[0];
        entry->command_base_addr = buf[1];
@@ -551,7 +567,7 @@ static int rmi_scan_pdt_page(struct rmi_device *rmi_dev,
        int retval;
 
        for (addr = pdt_start; addr >= pdt_end; addr -= RMI_PDT_ENTRY_SIZE) {
-               error = rmi_read_pdt_entry(rmi_dev, &pdt_entry, addr);
+               error = rmi_read_pdt_entry(rmi_dev, &pdt_entry, state, addr);
                if (error)
                        return error;
 
@@ -1028,9 +1044,11 @@ static int rmi_driver_remove(struct device *dev)
 }
 
 #ifdef CONFIG_OF
-static int rmi_driver_of_probe(struct device *dev,
-                               struct rmi_device_platform_data *pdata)
+static int rmi_driver_of_probe(struct rmi_device *rmi_dev,
+                              struct rmi_device_platform_data *pdata)
 {
+       struct device *dev = rmi_dev->xport->dev;
+       u8 buf[RMI_PDT_ENTRY_SIZE];
        int retval;
 
        retval = rmi_of_property_read_u32(dev, &pdata->reset_delay_ms,
@@ -1038,11 +1056,50 @@ static int rmi_driver_of_probe(struct device *dev,
        if (retval)
                return retval;
 
+       /*
+        * In some aftermerket touch ICs, the first PDT entry is empty and
+        * the function number register is 0. If so, the platform
+        * may have provided backup PDT entries in the device tree.
+        */
+
+       retval = rmi_read_block(rmi_dev, PDT_START_SCAN_LOCATION,
+                       buf, RMI_PDT_ENTRY_SIZE);
+       if (retval) {
+               dev_err(dev, "Read PDT entry at %#06x failed, code: %d.\n",
+                       PDT_START_SCAN_LOCATION, retval);
+               return retval;
+       }
+
+       if (!RMI4_END_OF_PDT(buf[5]))
+               return 0;
+
+       pdata->pdt_fallback_size = of_property_count_u8_elems(dev->of_node,
+                                                 "syna,pdt-fallback-desc");
+
+       /* The rmi4 driver would fail later anyway, so just error out now. */
+       if (pdata->pdt_fallback_size == -EINVAL) {
+               dev_err(dev, "First PDT entry is empty and no backup values 
provided\n");
+               return -EINVAL;
+       }
+
+       if (pdata->pdt_fallback_size < 0) {
+               dev_err(dev, "syna,pdt-fallback-desc property was not specified 
properly: %d\n",
+                       pdata->pdt_fallback_size);
+               return pdata->pdt_fallback_size;
+       }
+
+       pdata->pdt_fallback_desc = devm_kzalloc(dev, pdata->pdt_fallback_size, 
GFP_KERNEL);
+
+       retval = of_property_read_u8_array(dev->of_node, 
"syna,pdt-fallback-desc",
+               pdata->pdt_fallback_desc, pdata->pdt_fallback_size);
+       if (retval < 0)
+               return retval;
+
        return 0;
 }
 #else
-static inline int rmi_driver_of_probe(struct device *dev,
-                                       struct rmi_device_platform_data *pdata)
+static inline int rmi_driver_of_probe(struct rmi_device *rmi_dev,
+                                     struct rmi_device_platform_data *pdata)
 {
        return -ENODEV;
 }
@@ -1163,7 +1220,7 @@ static int rmi_driver_probe(struct device *dev)
        pdata = rmi_get_platform_data(rmi_dev);
 
        if (rmi_dev->xport->dev->of_node) {
-               retval = rmi_driver_of_probe(rmi_dev->xport->dev, pdata);
+               retval = rmi_driver_of_probe(rmi_dev, pdata);
                if (retval)
                        return retval;
        }
diff --git a/drivers/input/rmi4/rmi_driver.h b/drivers/input/rmi4/rmi_driver.h
index 
0ecbd19cefffe00ce7c8001db6479a2e213ac466..67a04133a4d85c56d80d0eafee65797319c75c54
 100644
--- a/drivers/input/rmi4/rmi_driver.h
+++ b/drivers/input/rmi4/rmi_driver.h
@@ -31,6 +31,8 @@
 #define RMI_PDT_FUNCTION_VERSION_MASK   0x60
 #define RMI_PDT_INT_SOURCE_COUNT_MASK   0x07
 
+#define RMI_OF_PDT_DESC_CELLS 2
+
 #define PDT_START_SCAN_LOCATION 0x00e9
 #define PDT_END_SCAN_LOCATION  0x0005
 #define RMI4_END_OF_PDT(id) ((id) == 0x00 || (id) == 0xff)
diff --git a/include/linux/rmi.h b/include/linux/rmi.h
index 
ab7eea01ab4274bfc9efcefcdb0cced6ec34966f..974597960b5ee61b670ab55a78c317710022d7cc
 100644
--- a/include/linux/rmi.h
+++ b/include/linux/rmi.h
@@ -214,6 +214,9 @@ struct rmi_device_platform_data {
        int reset_delay_ms;
        int irq;
 
+       u8 *pdt_fallback_desc;
+       int pdt_fallback_size;
+
        struct rmi_device_platform_data_spi spi_data;
 
        /* function handler pdata */

-- 
2.47.2



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