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SubjectRe: [PATCH 1/3] drivers/misc :UCC based TDM driver for MPC83xx platforms.
On Mon, 10 Dec 2007 17:34:44 +0530 (IST)
Poonam_Aggrwal-b10812 <b10812@freescale.com> wrote:

> From: Poonam Aggrwal <b10812@freescale.com>
>
> The UCC TDM driver basically multiplexes and demultiplexes data from
> different channels. It can interface with for example SLIC kind of devices
> to receive TDM data demultiplex it and send to upper applications. At the
> transmit end it receives data for different channels multiplexes it and
> sends them on the TDM channel. It internally uses TSA( Time Slot Assigner)
> which does multiplexing and demultiplexing, UCC to perform SDMA between
> host buffers and the TSA, CMX to connect TSA to UCC.
>
> This driver will run on MPC8323E-RDB platforms.
>
> ...
>
> +#define PREV_PHASE(x) ((x == 0) ? MAX_PHASE : (x - 1))
> +#define NEXT_PHASE(x) (((x + 1) > MAX_PHASE) ? 0 : (x + 1))

These macros can reference their arg more than once and are hence
dangerous. What does PREV_PHASE(foo++) do to foo?

And, in general: do not implement in cpp that which could have been
implemented in C.

> +static struct ucc_tdm_info utdm_primary_info = {
> + .uf_info = {
> + .tsa = 1,
> + .cdp = 1,
> + .cds = 1,
> + .ctsp = 1,
> + .ctss = 1,
> + .revd = 1,
> + .urfs = 0x128,
> + .utfs = 0x128,
> + .utfet = 0,
> + .utftt = 0x128,
> + .ufpt = 256,
> + .ttx_trx = UCC_FAST_GUMR_TRANSPARENT_TTX_TRX_TRANSPARENT,
> + .tenc = UCC_FAST_TX_ENCODING_NRZ,
> + .renc = UCC_FAST_RX_ENCODING_NRZ,
> + .tcrc = UCC_FAST_16_BIT_CRC,
> + .synl = UCC_FAST_SYNC_LEN_NOT_USED,
> + },
> + .ucc_busy = 0,
> +};
> +
> +static struct ucc_tdm_info utdm_info[8];
> +
> +static void dump_siram(struct tdm_ctrl *tdm_c)
> +{
> +#if defined(DEBUG)

Microscopic note: kernel code tends to do

#ifdef FOO

if only one identifier is being tested and

#if defined(FOO) && defined(BAR)

if more than one is being tested.

There is no rational reason for this ;)

> + int i;
> + u16 phy_num_ts;
> +
> + phy_num_ts = tdm_c->physical_num_ts;
> +
> + pr_debug("SI TxRAM dump\n");
> + /* each slot entry in SI RAM is of 2 bytes */
> + for (i = 0; i < phy_num_ts * 2; i++)
> + pr_debug("%x ", in_8(&qe_immr->sir.tx[i]));
> + pr_debug("\nSI RxRAM dump\n");
> + for (i = 0; i < phy_num_ts * 2; i++)
> + pr_debug("%x ", in_8(&qe_immr->sir.rx[i]));
> + pr_debug("\n");
> +#endif
> +}
> +
> +/*
> + * converts u-law compressed samples to linear PCM
> + * If the CONFIG_TDM_LINEAR_PCM flag is not set the
> + * TDM driver receives u-law compressed data from the
> + * SLIC device. This function converts the compressed
> + * data to linear PCM and sends it to upper layers.
> + */
> +static inline int ulaw2int(unsigned char log)
> +{
> + u32 sign, segment, temp, quant;
> + int val;
> +
> + temp = log ^ 0xFF;
> + sign = (temp & 0x80) >> 7;
> + segment = (temp & 0x70) >> 4;
> + quant = temp & 0x0F;
> + quant <<= 1;
> + quant += 33;
> + quant <<= segment;
> + if (sign)
> + val = 33 - quant;
> + else
> + val = quant - 33;
> +
> + val *= 4;
> + return val;
> +}
> +
> +/*
> + * converts linear PCM samples to u-law compressed format.
> + * If the CONFIG_TDM_LINEAR_PCM flag is not set the
> + * TDM driver calls this function to convert the PCM samples
> + * to u-law compressed format before sending them to SLIC
> + * device.
> + */
> +static inline u8 int2ulaw(short linear)
> +{
> + u8 quant, ret;
> + u16 output, absol, temp;
> + u32 i, sign;
> + char segment;
> +
> + ret = 0;
> + if (linear >= 0)
> + linear = (linear >> 2);
> + else
> + linear = (0xc000 | (linear >> 2));
> +
> + absol = abs(linear) + 33;
> + temp = absol;
> + sign = (linear >= 0) ? 1 : 0;
> + for (i = 0; i < 16; i++) {
> + output = temp & 0x8000;
> + if (output)
> + break;
> + temp <<= 1;
> + }
> + segment = 11 - i;
> + quant = (absol >> segment) & 0x0F;
> + segment--;
> + segment <<= 4;
> + output = segment + quant;
> + if (absol > 8191)
> + output = 0x7F;
> + if (sign)
> + ret ^= 0xFF;
> + else
> + ret ^= 0x7F;
> + return ret;
> +}

hrm, how many copies of ulaw/alaw conversion functions do we need in the
tree before someone writes a library function for it?

> + out_be16(&rx_bd->status, bd_status);
> + out_be32(&rx_bd->buf,
> + tdm_c->dma_input_addr + i * SAMPLE_DEPTH * act_num_ts);
> +
> + bd_status = (u16) ((T_R | T_CM | T_W) >> 16);
> + bd_len = SAMPLE_DEPTH * act_num_ts;
> + out_be16(&tx_bd->length, bd_len);
> + out_be16(&tx_bd->status, bd_status);
> + out_be32(&tx_bd->buf,
> + tdm_c->dma_output_addr + i * SAMPLE_DEPTH * act_num_ts);
> +
> + config_si(tdm_c);
> +
> + setbits32(&qe_immr->ic.qimr, (0x80000000 >> ucc));

The compiler treats 0xNNN constants as unsigned so this works OK. I'd have
put a UL on the end of the constant to be sure ;)

> +static int tdm_start(struct tdm_ctrl *tdm_c)
> +{
> + if (request_irq(tdm_c->ut_info->uf_info.irq, tdm_isr,
> + 0, "tdm", tdm_c)) {
> + printk(KERN_ERR "%s: request_irq for tdm_isr failed\n",
> + __FUNCTION__);
> + return -ENODEV;
> + }
> +
> + ucc_fast_enable(tdm_c->uf_private, COMM_DIR_RX | COMM_DIR_TX);
> +
> +#if !defined(CONFIG_TDM_LINEAR_PCM)
> + pr_info("%s 8-bit u-law compressed mode active\n", __FUNCTION__);
> +#else
> + pr_info("%s 16-bit linear pcm mode active with"
> + " slots 0 & 2\n", __FUNCTION__);
> +#endif

Is this the sort of thing which should be controlled at compile-time? I'd
have thought that a runtime control would be more appropriate (a sysfs knob
or a module parameter). Or just work it out automagically?


> + dump_siram(tdm_c);
> + dump_ucc(tdm_c);
> +
> + setbits8(&(qe_immr->si1.siglmr1_h), (0x1 << tdm_c->tdm_port));
> + pr_info("%s UCC based TDM enabled\n", __FUNCTION__);
> +
> + return 0;
> +}
>
> ...
>
> +static void tdm_read(u32 driver_handle, short chn_id, short *pcm_buffer,
> + short len)
> +{
> + int i;
> + u32 phase_rx;
> + /* point to where to start for the current phase data processing */
> + u32 temp_rx;
> +
> + struct tdm_ctrl *tdm_c = (struct tdm_ctrl *)(driver_handle);

eek. What are we doing here, casting a 32-bit quantity to a kernel pointer?

a) Seems to rule out ever using this driver on a 64-bit system

b) It's generally suspicious and indicates that some rethinking is needed.

> +#if !defined(CONFIG_TDM_LINEAR_PCM)
> + u8 *input_tdm_buffer = tdm_c->tdm_input_data;
> +
> +#else
> + u16 *input_tdm_buffer =
> + (u16 *)tdm_c->tdm_input_data;
> +
> +#endif
> + phase_rx = tdm_c->phase_rx;
> + phase_rx = PREV_PHASE(phase_rx);
> +
> + temp_rx = phase_rx * SAMPLE_DEPTH * EFF_ACTIVE_CH;
> +
> +#if defined(UCC_CACHE_SNOOPING_DISABLED)
> + flush_dcache_range((size_t) &input_tdm_buffer[temp_rx],
> + (size_t) &input_tdm_buffer[temp_rx +
> + SAMPLE_DEPTH * ACTIVE_CH]);
> +#endif

Again, is it appropriate that this behaviour be determined at compile-time?
This is very user- and packager- and distributor-unfriendly.

> + for (i = 0; i < len; i++) {
> +#if !defined(CONFIG_TDM_LINEAR_PCM)
> + pcm_buffer[i] =
> + ulaw2int(input_tdm_buffer[i * EFF_ACTIVE_CH +
> + temp_rx + chn_id]);
> +#else
> + pcm_buffer[i] =
> + input_tdm_buffer[i * EFF_ACTIVE_CH + temp_rx + chn_id];
> +#endif
> +
> + }
> +
> +}
> +
> +static int ucc_tdm_probe(struct of_device *ofdev,
> + const struct of_device_id *match)
> +{
> + struct device_node *np = ofdev->node;
> + struct resource res;
> + const unsigned int *prop;
> + u32 ucc_num, device_num, err, ret = 0;
> + struct device_node *np_tmp = NULL;
> + dma_addr_t physaddr;
> + void *tdm_buff;
> + struct ucc_tdm_info *ut_info;
> +
> + prop = of_get_property(np, "device-id", NULL);
> + ucc_num = *prop - 1;
> + if ((ucc_num < 0) || (ucc_num > 7))
> + return -ENODEV;
> +
> + ut_info = &utdm_info[ucc_num];
> + if (ut_info == NULL) {
> + printk(KERN_ERR "additional data missing\n");
> + return -ENODEV;
> + }
> + if (ut_info->ucc_busy) {
> + printk(KERN_ERR "UCC in use by another TDM driver instance\n");
> + return -EBUSY;
> + }
> +
> + ut_info->ucc_busy = 1;
> + tdm_ctrl[num_tdm_devices++] =
> + kzalloc(sizeof(struct tdm_ctrl), GFP_KERNEL);

Shouldn't this check for (num_tdm_devices > MAX_NUM_TDM_DEVICES))?

> + if (!tdm_ctrl[num_tdm_devices - 1]) {
> + printk(KERN_ERR "%s: no memory to allocate for"
> + " tdm control structure\n", __FUNCTION__);
> + num_tdm_devices--;
> + return -ENOMEM;
> + }
> + device_num = num_tdm_devices - 1;
> +
> + tdm_ctrl[device_num]->device = &ofdev->dev;
> + tdm_ctrl[device_num]->ut_info = ut_info;
> +
> + tdm_ctrl[device_num]->ut_info->uf_info.ucc_num = ucc_num;
> +
> + prop = of_get_property(np, "fsl,tdm-num", NULL);
> + if (prop == NULL) {
> + ret = -EINVAL;
> + goto get_property_error;
> + }
>
> ...
>
> +
> +#define SET_RX_SI_RAM(n, val) \
> + out_be16((u16 *)&qe_immr->sir.rx[(n)*2], (u16)(val))
> +
> +#define SET_TX_SI_RAM(n, val) \
> + out_be16((u16 *)&qe_immr->sir.tx[(n)*2], (u16)(val))

I don't think there's anything which requires that these be imlemented in
the preprocessor?

> +struct tdm_cfg {
> + u8 com_pin; /* Common receive and transmit pins
> + * 0 = separate pins
> + * 1 = common pins
> + */
> +
> + u8 fr_sync_level; /* SLx bit Frame Sync Polarity
> + * 0 = L1R/TSYNC active logic "1"
> + * 1 = L1R/TSYNC active logic "0"
> + */
> +
> + u8 clk_edge; /* CEx bit Tx Rx Clock Edge
> + * 0 = TX data on rising edge of clock
> + * RX data on falling edge
> + * 1 = TX data on falling edge of clock
> + * RX data on rising edge
> + */
> +
> + u8 fr_sync_edge; /* FEx bit Frame sync edge
> + * Determine when the sync pulses are sampled
> + * 0 = Falling edge
> + * 1 = Rising edge
> + */
> +
> + u8 rx_fr_sync_delay; /* TFSDx/RFSDx bits Frame Sync Delay
> + * 00 = no bit delay
> + * 01 = 1 bit delay
> + * 10 = 2 bit delay
> + * 11 = 3 bit delay
> + */
> +
> + u8 tx_fr_sync_delay; /* TFSDx/RFSDx bits Frame Sync Delay
> + * 00 = no bit delay
> + * 01 = 1 bit delay
> + * 10 = 2 bit delay
> + * 11 = 3 bit delay
> + */
> +
> + u8 active_num_ts; /* Number of active time slots in TDM
> + * assume same active Rx/Tx time slots
> + */
> +};

Nice commenting.




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