w1: complete the 1-wire (w1) ds1wm driver search algorithm
authorJean-François Dagenais <dagenaisj@sonatest.com>
Thu, 26 May 2011 23:26:02 +0000 (16:26 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 27 May 2011 00:12:38 +0000 (17:12 -0700)
This adds multi-slave support of the w1 bus for the ds1wm Synthesizable
1-Wire Bus Master.  Also many fixes and tweaks based on the rev3 of the
datasheet http://datasheets.maxim-ic.com/en/ds/DS1WM.pdf

Signed-off-by: Jean-François Dagenais <dagenaisj@sonatest.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
Cc: Matt Reimer <mreimer@vpop.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/w1/masters/Kconfig
drivers/w1/masters/ds1wm.c

index 7c608c5ccf84f856cf476d28c7b01f87c3f1c5f9..00d615d7aa216d52387e8d67952851a42802a326 100644 (file)
@@ -42,7 +42,7 @@ config W1_MASTER_MXC
 
 config W1_MASTER_DS1WM
        tristate "Maxim DS1WM 1-wire busmaster"
-       depends on W1 && ARM && HAVE_CLK
+       depends on W1
        help
          Say Y here to enable the DS1WM 1-wire driver, such as that
          in HP iPAQ devices like h5xxx, h2200, and ASIC3-based like
index 0855d6cce3c1f80a688d0cc687b717cbc05eec76..ad57593d224a1f3200a0ef818b36bcb22f6fdf75 100644 (file)
@@ -33,6 +33,7 @@
 #define DS1WM_INT      0x02    /* R/W interrupt status */
 #define DS1WM_INT_EN   0x03    /* R/W interrupt enable */
 #define DS1WM_CLKDIV   0x04    /* R/W 5 bits of divisor and pre-scale */
+#define DS1WM_CNTRL    0x05    /* R/W master control register (not used yet) */
 
 #define DS1WM_CMD_1W_RESET  (1 << 0)   /* force reset on 1-wire bus */
 #define DS1WM_CMD_SRA      (1 << 1)    /* enable Search ROM accelerator mode */
@@ -56,6 +57,7 @@
 #define DS1WM_INTEN_ERSRF   (1 << 5)   /* enable rx shift register full int */
 #define DS1WM_INTEN_DQO            (1 << 6)    /* enable direct bus driving ops */
 
+#define DS1WM_INTEN_NOT_IAS (~DS1WM_INTEN_IAS) /* all but INTR active state */
 
 #define DS1WM_TIMEOUT (HZ * 5)
 
@@ -63,41 +65,50 @@ static struct {
        unsigned long freq;
        unsigned long divisor;
 } freq[] = {
-       { 4000000, 0x8 },
-       { 5000000, 0x2 },
-       { 6000000, 0x5 },
-       { 7000000, 0x3 },
-       { 8000000, 0xc },
-       { 10000000, 0x6 },
-       { 12000000, 0x9 },
-       { 14000000, 0x7 },
-       { 16000000, 0x10 },
-       { 20000000, 0xa },
-       { 24000000, 0xd },
-       { 28000000, 0xb },
-       { 32000000, 0x14 },
-       { 40000000, 0xe },
-       { 48000000, 0x11 },
-       { 56000000, 0xf },
-       { 64000000, 0x18 },
-       { 80000000, 0x12 },
-       { 96000000, 0x15 },
-       { 112000000, 0x13 },
-       { 128000000, 0x1c },
+       {   1000000, 0x80 },
+       {   2000000, 0x84 },
+       {   3000000, 0x81 },
+       {   4000000, 0x88 },
+       {   5000000, 0x82 },
+       {   6000000, 0x85 },
+       {   7000000, 0x83 },
+       {   8000000, 0x8c },
+       {  10000000, 0x86 },
+       {  12000000, 0x89 },
+       {  14000000, 0x87 },
+       {  16000000, 0x90 },
+       {  20000000, 0x8a },
+       {  24000000, 0x8d },
+       {  28000000, 0x8b },
+       {  32000000, 0x94 },
+       {  40000000, 0x8e },
+       {  48000000, 0x91 },
+       {  56000000, 0x8f },
+       {  64000000, 0x98 },
+       {  80000000, 0x92 },
+       {  96000000, 0x95 },
+       { 112000000, 0x93 },
+       { 128000000, 0x9c },
+/* you can continue this table, consult the OPERATION - CLOCK DIVISOR
+   section of the ds1wm spec sheet. */
 };
 
 struct ds1wm_data {
-       void            __iomem *map;
-       int             bus_shift; /* # of shifts to calc register offsets */
+       void     __iomem *map;
+       int      bus_shift; /* # of shifts to calc register offsets */
        struct platform_device *pdev;
-       const struct mfd_cell *cell;
-       int             irq;
-       int             active_high;
-       int             slave_present;
-       void            *reset_complete;
-       void            *read_complete;
-       void            *write_complete;
-       u8              read_byte; /* last byte received */
+       const struct mfd_cell   *cell;
+       int      irq;
+       int      slave_present;
+       void     *reset_complete;
+       void     *read_complete;
+       void     *write_complete;
+       int      read_error;
+       /* last byte received */
+       u8       read_byte;
+       /* byte to write that makes all intr disabled, */
+       /* considering active_state (IAS) (optimization) */
+       u8       int_en_reg_none;
 };
 
 static inline void ds1wm_write_register(struct ds1wm_data *ds1wm_data, u32 reg,
@@ -115,23 +126,39 @@ static inline u8 ds1wm_read_register(struct ds1wm_data *ds1wm_data, u32 reg)
 static irqreturn_t ds1wm_isr(int isr, void *data)
 {
        struct ds1wm_data *ds1wm_data = data;
-       u8 intr = ds1wm_read_register(ds1wm_data, DS1WM_INT);
+       u8 intr;
+       u8 inten = ds1wm_read_register(ds1wm_data, DS1WM_INT_EN);
+       /* if no bits are set in int enable register (except the IAS)
+       than go no further, reading the regs below has side effects */
+       if (!(inten & DS1WM_INTEN_NOT_IAS))
+               return IRQ_NONE;
 
-       ds1wm_data->slave_present = (intr & DS1WM_INT_PDR) ? 0 : 1;
+       ds1wm_write_register(ds1wm_data,
+               DS1WM_INT_EN, ds1wm_data->int_en_reg_none);
 
-       if ((intr & DS1WM_INT_PD) && ds1wm_data->reset_complete)
-               complete(ds1wm_data->reset_complete);
+       /* this read action clears the INTR and certain flags in ds1wm */
+       intr = ds1wm_read_register(ds1wm_data, DS1WM_INT);
 
-       if ((intr & DS1WM_INT_TSRE) && ds1wm_data->write_complete)
-               complete(ds1wm_data->write_complete);
+       ds1wm_data->slave_present = (intr & DS1WM_INT_PDR) ? 0 : 1;
 
+       if ((intr & DS1WM_INT_TSRE) && ds1wm_data->write_complete) {
+               inten &= ~DS1WM_INTEN_ETMT;
+               complete(ds1wm_data->write_complete);
+       }
        if (intr & DS1WM_INT_RBF) {
+               /* this read clears the RBF flag */
                ds1wm_data->read_byte = ds1wm_read_register(ds1wm_data,
-                                                           DS1WM_DATA);
+               DS1WM_DATA);
+               inten &= ~DS1WM_INTEN_ERBF;
                if (ds1wm_data->read_complete)
                        complete(ds1wm_data->read_complete);
        }
+       if ((intr & DS1WM_INT_PD) && ds1wm_data->reset_complete) {
+               inten &= ~DS1WM_INTEN_EPD;
+               complete(ds1wm_data->reset_complete);
+       }
 
+       ds1wm_write_register(ds1wm_data, DS1WM_INT_EN, inten);
        return IRQ_HANDLED;
 }
 
@@ -142,33 +169,19 @@ static int ds1wm_reset(struct ds1wm_data *ds1wm_data)
 
        ds1wm_data->reset_complete = &reset_done;
 
+       /* enable Presence detect only */
        ds1wm_write_register(ds1wm_data, DS1WM_INT_EN, DS1WM_INTEN_EPD |
-               (ds1wm_data->active_high ? DS1WM_INTEN_IAS : 0));
+       ds1wm_data->int_en_reg_none);
 
        ds1wm_write_register(ds1wm_data, DS1WM_CMD, DS1WM_CMD_1W_RESET);
 
        timeleft = wait_for_completion_timeout(&reset_done, DS1WM_TIMEOUT);
        ds1wm_data->reset_complete = NULL;
        if (!timeleft) {
-               dev_err(&ds1wm_data->pdev->dev, "reset failed\n");
+               dev_err(&ds1wm_data->pdev->dev, "reset failed, timed out\n");
                return 1;
        }
 
-       /* Wait for the end of the reset. According to the specs, the time
-        * from when the interrupt is asserted to the end of the reset is:
-        *     tRSTH  - tPDH  - tPDL - tPDI
-        *     625 us - 60 us - 240 us - 100 ns = 324.9 us
-        *
-        * We'll wait a bit longer just to be sure.
-        * Was udelay(500), but if it is going to busywait the cpu that long,
-        * might as well come back later.
-        */
-       msleep(1);
-
-       ds1wm_write_register(ds1wm_data, DS1WM_INT_EN,
-               DS1WM_INTEN_ERBF | DS1WM_INTEN_ETMT | DS1WM_INTEN_EPD |
-               (ds1wm_data->active_high ? DS1WM_INTEN_IAS : 0));
-
        if (!ds1wm_data->slave_present) {
                dev_dbg(&ds1wm_data->pdev->dev, "reset: no devices found\n");
                return 1;
@@ -179,26 +192,47 @@ static int ds1wm_reset(struct ds1wm_data *ds1wm_data)
 
 static int ds1wm_write(struct ds1wm_data *ds1wm_data, u8 data)
 {
+       unsigned long timeleft;
        DECLARE_COMPLETION_ONSTACK(write_done);
        ds1wm_data->write_complete = &write_done;
 
+       ds1wm_write_register(ds1wm_data, DS1WM_INT_EN,
+       ds1wm_data->int_en_reg_none | DS1WM_INTEN_ETMT);
+
        ds1wm_write_register(ds1wm_data, DS1WM_DATA, data);
 
-       wait_for_completion_timeout(&write_done, DS1WM_TIMEOUT);
+       timeleft = wait_for_completion_timeout(&write_done, DS1WM_TIMEOUT);
+
        ds1wm_data->write_complete = NULL;
+       if (!timeleft) {
+               dev_err(&ds1wm_data->pdev->dev, "write failed, timed out\n");
+               return -ETIMEDOUT;
+       }
 
        return 0;
 }
 
-static int ds1wm_read(struct ds1wm_data *ds1wm_data, unsigned char write_data)
+static u8 ds1wm_read(struct ds1wm_data *ds1wm_data, unsigned char write_data)
 {
+       unsigned long timeleft;
+       u8 intEnable = DS1WM_INTEN_ERBF | ds1wm_data->int_en_reg_none;
        DECLARE_COMPLETION_ONSTACK(read_done);
+
+       ds1wm_read_register(ds1wm_data, DS1WM_DATA);
+
        ds1wm_data->read_complete = &read_done;
+       ds1wm_write_register(ds1wm_data, DS1WM_INT_EN, intEnable);
 
-       ds1wm_write(ds1wm_data, write_data);
-       wait_for_completion_timeout(&read_done, DS1WM_TIMEOUT);
-       ds1wm_data->read_complete = NULL;
+       ds1wm_write_register(ds1wm_data, DS1WM_DATA, write_data);
+       timeleft = wait_for_completion_timeout(&read_done, DS1WM_TIMEOUT);
 
+       ds1wm_data->read_complete = NULL;
+       if (!timeleft) {
+               dev_err(&ds1wm_data->pdev->dev, "read failed, timed out\n");
+               ds1wm_data->read_error = -ETIMEDOUT;
+               return 0xFF;
+       }
+       ds1wm_data->read_error = 0;
        return ds1wm_data->read_byte;
 }
 
@@ -206,8 +240,8 @@ static int ds1wm_find_divisor(int gclk)
 {
        int i;
 
-       for (i = 0; i < ARRAY_SIZE(freq); i++)
-               if (gclk <= freq[i].freq)
+       for (i = ARRAY_SIZE(freq)-1; i >= 0; --i)
+               if (gclk >= freq[i].freq)
                        return freq[i].divisor;
 
        return 0;
@@ -222,6 +256,8 @@ static void ds1wm_up(struct ds1wm_data *ds1wm_data)
                ds1wm_data->cell->enable(ds1wm_data->pdev);
 
        divisor = ds1wm_find_divisor(plat->clock_rate);
+       dev_dbg(&ds1wm_data->pdev->dev,
+               "found divisor 0x%x for clock %d\n", divisor, plat->clock_rate);
        if (divisor == 0) {
                dev_err(&ds1wm_data->pdev->dev,
                        "no suitable divisor for %dHz clock\n",
@@ -242,7 +278,7 @@ static void ds1wm_down(struct ds1wm_data *ds1wm_data)
 
        /* Disable interrupts. */
        ds1wm_write_register(ds1wm_data, DS1WM_INT_EN,
-                            ds1wm_data->active_high ? DS1WM_INTEN_IAS : 0);
+               ds1wm_data->int_en_reg_none);
 
        if (ds1wm_data->cell->disable)
                ds1wm_data->cell->disable(ds1wm_data->pdev);
@@ -279,41 +315,121 @@ static void ds1wm_search(void *data, struct w1_master *master_dev,
 {
        struct ds1wm_data *ds1wm_data = data;
        int i;
-       unsigned long long rom_id;
-
-       /* XXX We need to iterate for multiple devices per the DS1WM docs.
-        * See http://www.maxim-ic.com/appnotes.cfm/appnote_number/120. */
-       if (ds1wm_reset(ds1wm_data))
-               return;
-
-       ds1wm_write(ds1wm_data, search_type);
-       ds1wm_write_register(ds1wm_data, DS1WM_CMD, DS1WM_CMD_SRA);
-
-       for (rom_id = 0, i = 0; i < 16; i++) {
-
-               unsigned char resp, r, d;
-
-               resp = ds1wm_read(ds1wm_data, 0x00);
-
-               r = ((resp & 0x02) >> 1) |
-                   ((resp & 0x08) >> 2) |
-                   ((resp & 0x20) >> 3) |
-                   ((resp & 0x80) >> 4);
-
-               d = ((resp & 0x01) >> 0) |
-                   ((resp & 0x04) >> 1) |
-                   ((resp & 0x10) >> 2) |
-                   ((resp & 0x40) >> 3);
-
-               rom_id |= (unsigned long long) r << (i * 4);
-
-       }
-       dev_dbg(&ds1wm_data->pdev->dev, "found 0x%08llX\n", rom_id);
-
-       ds1wm_write_register(ds1wm_data, DS1WM_CMD, ~DS1WM_CMD_SRA);
-       ds1wm_reset(ds1wm_data);
-
-       slave_found(master_dev, rom_id);
+       int ms_discrep_bit = -1;
+       u64 r = 0; /* holds the progress of the search */
+       u64 r_prime, d;
+       unsigned slaves_found = 0;
+       unsigned int pass = 0;
+
+       dev_dbg(&ds1wm_data->pdev->dev, "search begin\n");
+       while (true) {
+               ++pass;
+               if (pass > 100) {
+                       dev_dbg(&ds1wm_data->pdev->dev,
+                               "too many attempts (100), search aborted\n");
+                       return;
+               }
+
+               if (ds1wm_reset(ds1wm_data)) {
+                       dev_dbg(&ds1wm_data->pdev->dev,
+                               "pass: %d reset error (or no slaves)\n", pass);
+                       break;
+               }
+
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d r : %0#18llx writing SEARCH_ROM\n", pass, r);
+               ds1wm_write(ds1wm_data, search_type);
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d entering ASM\n", pass);
+               ds1wm_write_register(ds1wm_data, DS1WM_CMD, DS1WM_CMD_SRA);
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d begining nibble loop\n", pass);
+
+               r_prime = 0;
+               d = 0;
+               /* we work one nibble at a time */
+               /* each nibble is interleaved to form a byte */
+               for (i = 0; i < 16; i++) {
+
+                       unsigned char resp, _r, _r_prime, _d;
+
+                       _r = (r >> (4*i)) & 0xf;
+                       _r = ((_r & 0x1) << 1) |
+                       ((_r & 0x2) << 2) |
+                       ((_r & 0x4) << 3) |
+                       ((_r & 0x8) << 4);
+
+                       /* writes _r, then reads back: */
+                       resp = ds1wm_read(ds1wm_data, _r);
+
+                       if (ds1wm_data->read_error) {
+                               dev_err(&ds1wm_data->pdev->dev,
+                               "pass: %d nibble: %d read error\n", pass, i);
+                               break;
+                       }
+
+                       _r_prime = ((resp & 0x02) >> 1) |
+                       ((resp & 0x08) >> 2) |
+                       ((resp & 0x20) >> 3) |
+                       ((resp & 0x80) >> 4);
+
+                       _d = ((resp & 0x01) >> 0) |
+                       ((resp & 0x04) >> 1) |
+                       ((resp & 0x10) >> 2) |
+                       ((resp & 0x40) >> 3);
+
+                       r_prime |= (unsigned long long) _r_prime << (i * 4);
+                       d |= (unsigned long long) _d << (i * 4);
+
+               }
+               if (ds1wm_data->read_error) {
+                       dev_err(&ds1wm_data->pdev->dev,
+                               "pass: %d read error, retrying\n", pass);
+                       break;
+               }
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d r\': %0#18llx d:%0#18llx\n",
+                       pass, r_prime, d);
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d nibble loop complete, exiting ASM\n", pass);
+               ds1wm_write_register(ds1wm_data, DS1WM_CMD, ~DS1WM_CMD_SRA);
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d resetting bus\n", pass);
+               ds1wm_reset(ds1wm_data);
+               if ((r_prime & ((u64)1 << 63)) && (d & ((u64)1 << 63))) {
+                       dev_err(&ds1wm_data->pdev->dev,
+                               "pass: %d bus error, retrying\n", pass);
+                       continue; /* start over */
+               }
+
+
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d found %0#18llx\n", pass, r_prime);
+               slave_found(master_dev, r_prime);
+               ++slaves_found;
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d complete, preparing next pass\n", pass);
+
+               /* any discrepency found which we already choose the
+                  '1' branch is now is now irrelevant we reveal the
+                  next branch with this: */
+               d &= ~r;
+               /* find last bit set, i.e. the most signif. bit set */
+               ms_discrep_bit = fls64(d) - 1;
+               dev_dbg(&ds1wm_data->pdev->dev,
+                       "pass: %d new d:%0#18llx MS discrep bit:%d\n",
+                       pass, d, ms_discrep_bit);
+
+               /* prev_ms_discrep_bit = ms_discrep_bit;
+                  prepare for next ROM search:             */
+               if (ms_discrep_bit == -1)
+                       break;
+
+               r = (r &  ~(~0ull << (ms_discrep_bit))) | 1 << ms_discrep_bit;
+       } /* end while true */
+       dev_dbg(&ds1wm_data->pdev->dev,
+               "pass: %d total: %d search done ms d bit pos: %d\n", pass,
+               slaves_found, ms_discrep_bit);
 }
 
 /* --------------------------------------------------------------------- */
@@ -373,15 +489,15 @@ static int ds1wm_probe(struct platform_device *pdev)
                goto err1;
        }
        ds1wm_data->irq = res->start;
-       ds1wm_data->active_high = plat->active_high;
+       ds1wm_data->int_en_reg_none = (plat->active_high ? DS1WM_INTEN_IAS : 0);
 
        if (res->flags & IORESOURCE_IRQ_HIGHEDGE)
                irq_set_irq_type(ds1wm_data->irq, IRQ_TYPE_EDGE_RISING);
        if (res->flags & IORESOURCE_IRQ_LOWEDGE)
                irq_set_irq_type(ds1wm_data->irq, IRQ_TYPE_EDGE_FALLING);
 
-       ret = request_irq(ds1wm_data->irq, ds1wm_isr, IRQF_DISABLED,
-                         "ds1wm", ds1wm_data);
+       ret = request_irq(ds1wm_data->irq, ds1wm_isr,
+                       IRQF_DISABLED | IRQF_SHARED, "ds1wm", ds1wm_data);
        if (ret)
                goto err1;
 
@@ -468,5 +584,6 @@ module_exit(ds1wm_exit);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>, "
-             "Matt Reimer <mreimer@vpop.net>");
+       "Matt Reimer <mreimer@vpop.net>,"
+       "Jean-Francois Dagenais <dagenaisj@sonatest.com>");
 MODULE_DESCRIPTION("DS1WM w1 busmaster driver");