drivers/fsi: Add error handling for slave

This change implements error handling in the FSI core, by cleaining up
and retrying failed operations, using the SISC, TERM and BREAK
facilities.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index db54561161acaa31c04e60faeea2ce444e2b2166..c9ff8d3b3f031e8cfb826795a466f8eab9a235de 100644 (file)
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -46,7 +46,9 @@ static const int engine_page_size = 0x400;
 /*
  * FSI slave engine control register offsets
  */
-#define FSI_SMODE                      0x0     /* R/W: Mode register */
+#define FSI_SMODE              0x0     /* R/W: Mode register */
+#define FSI_SISC               0x8     /* R/W: Interrupt condition */
+#define FSI_SSTAT              0x14    /* R  : Slave status */
 
 /*
  * SMODE fields
@@ -77,10 +79,14 @@ struct fsi_slave {
 #define to_fsi_master(d) container_of(d, struct fsi_master, dev)
 #define to_fsi_slave(d) container_of(d, struct fsi_slave, dev)
 
+static const int slave_retries = 2;
+static int discard_errors;
+
 static int fsi_master_read(struct fsi_master *master, int link,
                uint8_t slave_id, uint32_t addr, void *val, size_t size);
 static int fsi_master_write(struct fsi_master *master, int link,
                uint8_t slave_id, uint32_t addr, const void *val, size_t size);
+static int fsi_master_break(struct fsi_master *master, int link);
 
 /*
  * fsi_device_read() / fsi_device_write() / fsi_device_peek()
@@ -173,18 +179,107 @@ static int fsi_slave_calc_addr(struct fsi_slave *slave, uint32_t *addrp,
        return 0;
 }
 
+int fsi_slave_report_and_clear_errors(struct fsi_slave *slave)
+{
+       struct fsi_master *master = slave->master;
+       uint32_t irq, stat;
+       int rc, link;
+       uint8_t id;
+
+       link = slave->link;
+       id = slave->id;
+
+       rc = fsi_master_read(master, link, id, FSI_SLAVE_BASE + FSI_SISC,
+                       &irq, sizeof(irq));
+       if (rc)
+               return rc;
+
+       rc =  fsi_master_read(master, link, id, FSI_SLAVE_BASE + FSI_SSTAT,
+                       &stat, sizeof(stat));
+       if (rc)
+               return rc;
+
+       dev_info(&slave->dev, "status: 0x%08x, sisc: 0x%08x\n",
+                       be32_to_cpu(stat), be32_to_cpu(irq));
+
+       /* clear interrupts */
+       return fsi_master_write(master, link, id, FSI_SLAVE_BASE + FSI_SISC,
+                       &irq, sizeof(irq));
+}
+
+static int fsi_slave_set_smode(struct fsi_master *master, int link, int id);
+
+int fsi_slave_handle_error(struct fsi_slave *slave, bool write, uint32_t addr,
+               size_t size)
+{
+       struct fsi_master *master = slave->master;
+       int rc, link;
+       uint32_t reg;
+       uint8_t id;
+
+       if (discard_errors)
+               return -1;
+
+       link = slave->link;
+       id = slave->id;
+
+       dev_dbg(&slave->dev, "handling error on %s to 0x%08x[%zd]",
+                       write ? "write" : "read", addr, size);
+
+       /* try a simple clear of error conditions, which may fail if we've lost
+        * communication with the slave
+        */
+       rc = fsi_slave_report_and_clear_errors(slave);
+       if (!rc)
+               return 0;
+
+       /* send a TERM and retry */
+       if (master->term) {
+               rc = master->term(master, link, id);
+               if (!rc) {
+                       rc = fsi_master_read(master, link, id, 0,
+                                       &reg, sizeof(reg));
+                       if (!rc)
+                               rc = fsi_slave_report_and_clear_errors(slave);
+                       if (!rc)
+                               return 0;
+               }
+       }
+
+       /* getting serious, reset the slave via BREAK */
+       rc = fsi_master_break(master, link);
+       if (rc)
+               return rc;
+
+       rc = fsi_slave_set_smode(master, link, id);
+       if (rc)
+               return rc;
+
+       return fsi_slave_report_and_clear_errors(slave);
+}
+
 int fsi_slave_read(struct fsi_slave *slave, uint32_t addr,
                        void *val, size_t size)
 {
        uint8_t id = slave->id;
-       int rc;
+       int rc, err_rc, i;
 
        rc = fsi_slave_calc_addr(slave, &addr, &id);
        if (rc)
                return rc;
 
-       return fsi_master_read(slave->master, slave->link, id,
-                       addr, val, size);
+       for (i = 0; i < slave_retries; i++) {
+               rc = fsi_master_read(slave->master, slave->link,
+                               id, addr, val, size);
+               if (!rc)
+                       break;
+
+               err_rc = fsi_slave_handle_error(slave, false, addr, size);
+               if (err_rc)
+                       break;
+       }
+
+       return rc;
 }
 EXPORT_SYMBOL_GPL(fsi_slave_read);
 
@@ -192,14 +287,24 @@ int fsi_slave_write(struct fsi_slave *slave, uint32_t addr,
                        const void *val, size_t size)
 {
        uint8_t id = slave->id;
-       int rc;
+       int rc, err_rc, i;
 
        rc = fsi_slave_calc_addr(slave, &addr, &id);
        if (rc)
                return rc;
 
-       return fsi_master_write(slave->master, slave->link, id,
-                       addr, val, size);
+       for (i = 0; i < slave_retries; i++) {
+               rc = fsi_master_write(slave->master, slave->link,
+                               id, addr, val, size);
+               if (!rc)
+                       break;
+
+               err_rc = fsi_slave_handle_error(slave, true, addr, size);
+               if (err_rc)
+                       break;
+       }
+
+       return rc;
 }
 EXPORT_SYMBOL_GPL(fsi_slave_write);
 
@@ -770,3 +875,5 @@ static void fsi_exit(void)
 
 module_init(fsi_init);
 module_exit(fsi_exit);
+module_param(discard_errors, int, 0664);
+MODULE_PARM_DESC(discard_errors, "Don't invoke error handling on bus accesses");