[RFC PATCH 16/19] hw/sd/sdcard: Add mmc SWITCH function support (CMD6)

[Philippe Mathieu-Daudé]

From: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>

switch operation in mmc cards, updated the ext_csd register to
request changes in card operations. Here we implement similar
sequence but requests are mostly dummy and make no change.

Implement SWITCH_ERROR if the write operation offset goes beyond
length of ext_csd.

Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/sd/sd.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/hw/sd/sd.c b/hw/sd/sd.c
index ae5e73175e..e7d8b9c0fb 100644
--- a/hw/sd/sd.c
+++ b/hw/sd/sd.c
@@ -625,6 +625,7 @@ static bool sd_req_rca_same(SDState *s, SDRequest req)
 FIELD(CSR, AKE_SEQ_ERROR,               3,  1)
 FIELD(CSR, APP_CMD,                     5,  1)
 FIELD(CSR, FX_EVENT,                    6,  1)
+FIELD(CSR, SWITCH_ERROR,                7,  1)
 FIELD(CSR, READY_FOR_DATA,              8,  1)
 FIELD(CSR, CURRENT_STATE,               9,  4)
 FIELD(CSR, ERASE_RESET,                13,  1)
@@ -1075,6 +1076,43 @@ static uint32_t sd_wpbits(SDState *sd, uint64_t addr)
     return ret;
 }
 
+enum {
+    MMC_CMD6_ACCESS_COMMAND_SET = 0,
+    MMC_CMD6_ACCESS_SET_BITS,
+    MMC_CMD6_ACCESS_CLEAR_BITS,
+    MMC_CMD6_ACCESS_WRITE_BYTE,
+};
+
+static void mmc_function_switch(SDState *sd, uint32_t arg)
+{
+    uint32_t access = extract32(arg, 24, 2);
+    uint32_t index = extract32(arg, 16, 8);
+    uint32_t value = extract32(arg, 8, 8);
+    uint8_t b = sd->ext_csd[index];
+
+    switch (access) {
+    case MMC_CMD6_ACCESS_COMMAND_SET:
+        qemu_log_mask(LOG_UNIMP, "MMC Command set switching not supported\n");
+        return;
+    case MMC_CMD6_ACCESS_SET_BITS:
+        b |= value;
+        break;
+    case MMC_CMD6_ACCESS_CLEAR_BITS:
+        b &= ~value;
+        break;
+    case MMC_CMD6_ACCESS_WRITE_BYTE:
+        b = value;
+        break;
+    }
+
+    if (index >= 192) {
+        sd->card_status |= R_CSR_SWITCH_ERROR_MASK;
+        return;
+    }
+
+    sd->ext_csd[index] = b;
+}
+
 static void sd_function_switch(SDState *sd, uint32_t arg)
 {
     int i, mode, new_func;
@@ -1398,6 +1436,19 @@ static sd_rsp_type_t sd_cmd_SWITCH_FUNCTION(SDState *sd, 
SDRequest req)
     return sd_cmd_to_sendingdata(sd, req, 0, NULL, 64);
 }
 
+static sd_rsp_type_t emmc_cmd_SWITCH(SDState *sd, SDRequest req)
+{
+    switch (sd->state) {
+    case sd_transfer_state:
+        sd->state = sd_programming_state;
+        mmc_function_switch(sd, req.arg);
+        sd->state = sd_transfer_state;
+        return sd_r1b;
+    default:
+        return sd_invalid_state_for_cmd(sd, req);
+    }
+}
+
 /* CMD7 */
 static sd_rsp_type_t sd_cmd_DE_SELECT_CARD(SDState *sd, SDRequest req)
 {
@@ -2602,6 +2653,7 @@ static const SDProto sd_proto_emmc = {
         [3]  = {0,  sd_ac,   "SET_RELATIVE_ADDR", emmc_cmd_SET_RELATIVE_ADDR},
         [4]  = {0,  sd_bc,   "SEND_DSR", sd_cmd_unimplemented},
         [5]  = {0,  sd_ac,   "SLEEP/AWAKE", emmc_cmd_sleep_awake},
+        [6]  = {10, sd_adtc, "SWITCH", emmc_cmd_SWITCH},
         [7]  = {0,  sd_ac,   "(DE)SELECT_CARD", sd_cmd_DE_SELECT_CARD},
         [8]  = {0,  sd_adtc, "SEND_EXT_CSD", emmc_cmd_SEND_EXT_CSD},
         [9]  = {0,  sd_ac,   "SEND_CSD", sd_cmd_SEND_CSD},
-- 
2.41.0